// Package mcp implements the Oikos MCP interface (plan R3-10).
// Uses the official MCP Go SDK with Streamable HTTP transport.
package mcp

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/dtoro/oikos/internal/db"
	"github.com/google/jsonschema-go/jsonschema"
	"github.com/google/uuid"
	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/crypto/ssh"
)

// prop is one input-schema property (name → type + description).
type prop struct {
	name, typ, desc string
}

// objSchema builds an "object" JSON Schema from a list of properties. The
// MCP SDK requires every tool to declare an object input schema so tools
// are self-describing to the agent; a nil schema panics at registration.
func objSchema(props ...prop) *jsonschema.Schema {
	s := &jsonschema.Schema{Type: "object", Properties: map[string]*jsonschema.Schema{}}
	for _, p := range props {
		s.Properties[p.name] = &jsonschema.Schema{Type: p.typ, Description: p.desc}
	}
	return s
}

// NewHandler creates an http.Handler that serves the Oikos MCP server.
// agentID is the Hermes agent entity UUID; tool calls are logged to agent_activity.
func NewHandler(pool *db.Pool, token string, agentID uuid.UUID) http.Handler {
	s := newServer(pool, agentID)
	handler := mcp.NewStreamableHTTPHandler(func(r *http.Request) *mcp.Server {
		if token != "" {
			if r.Header.Get("Authorization") != "Bearer "+token {
				return nil
			}
		}
		return s
	}, nil)
	return handler
}

// toolHandler is the function signature registered via AddTool.
type toolHandler = mcp.ToolHandler

func newServer(pool *db.Pool, agentID uuid.UUID) *mcp.Server {
	s := mcp.NewServer(&mcp.Implementation{Name: "oikos", Version: "dev"}, &mcp.ServerOptions{
		Logger: slog.Default(),
	})

	register := func(tool *mcp.Tool, handler toolHandler) {
		s.AddTool(tool, withActivityLogging(pool, agentID, tool.Name, handler))
	}

	register(&mcp.Tool{Name: "get_entity", Description: "Get an entity by slug or UUID",
		InputSchema: objSchema(prop{"slug_or_id", "string", "Entity slug (e.g. host:hubris) or UUID"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		idOrSlug, _ := args["slug_or_id"].(string)
		return queryEntity(ctx, pool, idOrSlug), nil
	})

	register(&mcp.Tool{Name: "list_entities", Description: "List entities filtered by type, state, or search",
		InputSchema: objSchema(
			prop{"type", "string", "Filter by entity type"},
			prop{"state", "string", "Filter by lifecycle state"},
			prop{"q", "string", "Substring match on slug or name"},
			prop{"limit", "integer", "Max rows (default 50)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		limit := int(getFloat(args, "limit", 50))
		return queryRows(ctx, pool, `
			SELECT e.slug, e.type, e.name, e.state, e.version, e.created_at, e.updated_at
			FROM entities e
			WHERE ($1::text IS NULL OR e.type = $1)
			  AND ($2::text IS NULL OR e.state = $2)
			  AND ($3::text IS NULL OR e.slug ILIKE '%'||$3||'%' OR e.name ILIKE '%'||$3||'%')
			ORDER BY e.slug LIMIT $4`,
			nStr(args["type"]), nStr(args["state"]), nStr(args["q"]), limit), nil
	})

	register(&mcp.Tool{Name: "get_relations", Description: "Get relationships for an entity",
		InputSchema: objSchema(prop{"entity_id", "string", "Entity slug"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["entity_id"].(string)
		return queryRows(ctx, pool, `
			SELECT r.type, src.slug AS source, tgt.slug AS target
			FROM relationships r
			JOIN entities src ON src.id = r.source_id
			JOIN entities tgt ON tgt.id = r.target_id
			WHERE (src.slug = $1 OR tgt.slug = $1) AND r.valid_to IS NULL
			ORDER BY r.type`, slug), nil
	})

	register(&mcp.Tool{Name: "get_blast_radius", Description: "Find entities affected if this entity goes down",
		InputSchema: objSchema(
			prop{"entity_id", "string", "Entity slug"},
			prop{"depth", "integer", "Traversal depth (default 3)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["entity_id"].(string)
		depth := int(getFloat(args, "depth", 3))
		return queryRows(ctx, pool,
			"SELECT slug, CAST(depth AS int) FROM blast_radius((SELECT id FROM entities WHERE slug = $1), $2)",
			slug, depth), nil
	})

	register(&mcp.Tool{Name: "get_health_summary", Description: "Current fleet health summary",
		InputSchema: objSchema(),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		return queryRows(ctx, pool, `
			SELECT e.slug, e.type, st.health, st.last_check_at
			FROM entity_status st JOIN entities e ON e.id = st.entity_id
			ORDER BY e.slug`), nil
	})

	register(&mcp.Tool{Name: "get_audit_trail", Description: "Query the audit log",
		InputSchema: objSchema(prop{"entity_id", "string", "Filter by affected entity UUID"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		return queryRows(ctx, pool, `
			SELECT id, ts, actor_type, action, entity_id::text, method, path, correlation_id
			FROM audit_log
			WHERE ($1::text IS NULL OR entity_id::text = $1)
			ORDER BY ts DESC LIMIT 50`, nStr(args["entity_id"])), nil
	})

	register(&mcp.Tool{Name: "search_knowledge", Description: "Full-text search across documentation",
		InputSchema: objSchema(prop{"query", "string", "Search terms"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		q := nStr(args["query"])
		return queryRows(ctx, pool, `
			SELECT id, title, LEFT(content, 500) AS preview
			FROM knowledge_entities
			WHERE ($1::text IS NULL OR title ILIKE '%'||$1||'%' OR content ILIKE '%'||$1||'%')
			ORDER BY title LIMIT 20`, q), nil
	})

	register(&mcp.Tool{Name: "query_metrics", Description: "Query time-series metrics",
		InputSchema: objSchema(prop{"hours", "integer", "Look-back window in hours (default 24)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		hours := int(getFloat(args, "hours", 24))
		return queryRows(ctx, pool, `
			SELECT time_bucket('1 hour', ts) AS bucket,
			       entity_id::text, metric,
			       ROUND(avg(value)::numeric, 2) AS avg,
			       ROUND(min(value)::numeric, 2) AS min,
			       ROUND(max(value)::numeric, 2) AS max
			FROM metric_samples
			WHERE ts > now() - make_interval(hours => $1)
			GROUP BY bucket, entity_id, metric
			ORDER BY bucket DESC LIMIT 100`, hours), nil
	})

	// ─── Phase 4: new tools ──────────────────────────────────────────

	register(&mcp.Tool{Name: "get_signal_history", Description: "Query open and recent signals",
		InputSchema: objSchema(
			prop{"entity_slug", "string", "Filter by target entity slug"},
			prop{"state", "string", "Filter by signal state (raised, resolved)"},
			prop{"limit", "integer", "Max rows (default 50)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		limit := int(getFloat(args, "limit", 50))
		return queryRows(ctx, pool, `
			SELECT s.entity_id::text, s.kind, s.severity, s.state,
			       s.occurrence_count, e.slug AS target_slug,
			       s.first_seen_at, s.last_seen_at
			FROM signals s
			LEFT JOIN entities e ON e.id = s.target_entity_id
			WHERE ($1::text IS NULL OR e.slug = $1)
			  AND ($2::text IS NULL OR s.state = $2)
			ORDER BY s.last_seen_at DESC LIMIT $3`,
			nStr(args["entity_slug"]), nStr(args["state"]), limit), nil
	})

	register(&mcp.Tool{Name: "get_patterns", Description: "List learned action patterns",
		InputSchema: objSchema(
			prop{"status", "string", "Filter by status (hypothesized, validated, active)"},
			prop{"entity_type", "string", "Filter by applies_type"},
			prop{"action", "string", "Filter by action"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		return queryRows(ctx, pool, `
			SELECT p.entity_id::text, p.applies_type, p.action, p.pattern,
			       p.confidence, p.evidence_count, p.success_count, p.failure_count,
			       p.status, p.quarantined, p.version, p.last_validated_at
			FROM patterns p
			WHERE ($1::text IS NULL OR p.status = $1)
			  AND ($2::text IS NULL OR p.applies_type = $2)
			  AND ($3::text IS NULL OR p.action = $3)
			ORDER BY p.applies_type, p.action`,
			nStr(args["status"]), nStr(args["entity_type"]), nStr(args["action"])), nil
	})

	register(&mcp.Tool{Name: "get_skills", Description: "List available automation skills",
		InputSchema: objSchema(
			prop{"status", "string", "Filter by status (active, inactive, deprecated)"},
		),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		return queryRows(ctx, pool, `
			SELECT s.entity_id::text, s.version, s.name, LEFT(s.procedure::text, 300) AS procedure_preview,
			       s.applies_type, s.action, s.status, s.success_rate,
			       s.changed_by::text, s.change_reason, s.last_used_at
			FROM skills s
			WHERE ($1::text IS NULL OR s.status = $1)
			ORDER BY s.name, s.version DESC`,
			nStr(args["status"])), nil
	})

	register(&mcp.Tool{Name: "request_execution", Description: "Request a gated execution (Hermes-only mutation path). Supported actions: restart, systemctl, pct_exec, apt_upgrade.",
		InputSchema: objSchema(
			prop{"target", "string", "Target entity slug (e.g. lxc:caddy)"},
			prop{"action", "string", "Action: restart, systemctl, pct_exec, apt_upgrade"},
			prop{"params", "string", "Extra params: for systemctl use 'enable|disable|reload', for pct_exec use the shell command, for apt_upgrade use 'audit|upgrade'"},
		),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		targetSlug, _ := args["target"].(string)
		action, _ := args["action"].(string)
		params, _ := args["params"].(string)
		if targetSlug == "" || action == "" {
			return textResult("error: target and action required"), nil
		}

		var targetID uuid.UUID
		if err := pool.QueryRow(ctx, "SELECT id FROM entities WHERE slug = $1", targetSlug).Scan(&targetID); err != nil {
			return textResult(fmt.Sprintf("target not found: %s", targetSlug)), nil
		}

		id, _ := uuid.NewV7()
		correlationID := uuid.New().String()

		// Write execution record
		execSlug := "exec:" + targetSlug + ":" + id.String()[:8]
		pool.Exec(ctx, `INSERT INTO entities (id, slug, type, name, attributes) VALUES ($1, $2, 'execution', $3, '{}')`,
			id, execSlug, action+" on "+targetSlug)
		pool.Exec(ctx, `INSERT INTO executions (entity_id, target_entity_id, action, risk_class, status, correlation_id, agent_id) VALUES ($1, $2, $3, 'reversible_low', 'running', $4, $5)`,
			id, targetID, action+":"+params, correlationID, agentID)

		// Execute reversible actions immediately
		switch action {
		case "restart":
			host, user, err := resolveHost(ctx, pool, targetSlug)
			if err != nil {
				return textResult(fmt.Sprintf("resolve: %v", err)), nil
			}
			svc := strings.TrimPrefix(targetSlug, "lxc:")
			out, err := sshExec(ctx, host, user, fmt.Sprintf("systemctl restart %s 2>&1; sleep 1; systemctl is-active %s", svc, svc))
			result := fmt.Sprintf("restart %s: %s", svc, out)
			if err != nil {
				result = fmt.Sprintf("restart %s: ERROR %v", svc, err)
			}
			pool.Exec(ctx, `UPDATE executions SET status='completed', result=$2::jsonb WHERE entity_id=$1`,
				id, fmt.Sprintf(`{"output":"%s"}`, strings.ReplaceAll(out, "\n", "\\n")))
			return textResult(result), nil

		case "systemctl":
			svc := strings.TrimPrefix(targetSlug, "lxc:")
			if params == "enable" || params == "disable" {
				pool.Exec(ctx, `UPDATE executions SET status='pending_approval', risk_class='config_mutation' WHERE entity_id=$1`, id)
				createApproval(ctx, pool, id, targetID, "systemctl", svc+":"+params, "config_mutation")
				return textResult(fmt.Sprintf("systemctl %s on %s requires approval — execution %s queued", params, svc, id)), nil
			}
			host, user, err := resolveHost(ctx, pool, targetSlug)
			if err != nil {
				return textResult(fmt.Sprintf("resolve: %v", err)), nil
			}
			cmd := fmt.Sprintf("systemctl %s %s 2>&1; sleep 1; systemctl is-active %s", params, svc, svc)
			out, err := sshExec(ctx, host, user, cmd)
			result := fmt.Sprintf("systemctl %s %s: %s", params, svc, out)
			if err != nil {
				result = fmt.Sprintf("systemctl %s %s: ERROR %v", params, svc, err)
			}
			pool.Exec(ctx, `UPDATE executions SET status='completed', result=$2::jsonb WHERE entity_id=$1`,
				id, fmt.Sprintf(`{"output":"%s"}`, strings.ReplaceAll(out, "\n", "\\n")))
			return textResult(result), nil

		case "pct_exec":
			var pveID string
			if err := pool.QueryRow(ctx, "SELECT attributes->>'pve_id' FROM entities WHERE slug = $1", targetSlug).Scan(&pveID); err != nil || pveID == "" {
				return textResult(fmt.Sprintf("LXC not found: %s", targetSlug)), nil
			}
			// Resolve Proxmox host
			var hostSlug string
			pool.QueryRow(ctx, "SELECT attributes->>'host' FROM entities WHERE slug = $1", targetSlug).Scan(&hostSlug)
			if hostSlug == "" {
				hostSlug = "host:hubris" // default
			}
			host, user, err := resolveHost(ctx, pool, hostSlug)
			if err != nil {
				return textResult(fmt.Sprintf("resolve Proxmox host: %v", err)), nil
			}
			out, err := sshExec(ctx, host, user, fmt.Sprintf("pct exec %s -- %s 2>&1", pveID, params))
			result := fmt.Sprintf("pct exec %s: %s", pveID, out)
			if err != nil {
				result = fmt.Sprintf("pct exec %s: ERROR %v", pveID, err)
			}
			pool.Exec(ctx, `UPDATE executions SET status='completed', result=$2::jsonb WHERE entity_id=$1`,
				id, fmt.Sprintf(`{"output":"%s"}`, strings.ReplaceAll(out, "\n", "\\n")))
			return textResult(result), nil

		case "apt_upgrade":
			if params == "audit" {
				host, user, err := resolveHost(ctx, pool, targetSlug)
				if err != nil {
					return textResult(fmt.Sprintf("resolve: %v", err)), nil
				}
				out, err := sshExec(ctx, host, user, "apt update -qq 2>&1 >/dev/null; apt list --upgradable 2>/dev/null | tail -n +2 | wc -l; apt list --upgradable 2>/dev/null | tail -n +2 | head -20")
				if err != nil {
					return textResult(fmt.Sprintf("apt audit error: %v", err)), nil
				}
				return textResult("apt audit:\n" + out), nil
			}
			// upgrade requires approval — queue
			pool.Exec(ctx, `UPDATE executions SET status='pending_approval', risk_class='config_mutation' WHERE entity_id=$1`, id)
			createApproval(ctx, pool, id, targetID, "apt_upgrade", params, "config_mutation")
			return textResult(fmt.Sprintf("apt_upgrade on %s requires approval — execution %s queued", targetSlug, id)), nil

		default:
			return textResult(fmt.Sprintf("unknown action: %s. Supported: restart, systemctl, pct_exec, apt_upgrade", action)), nil
		}
	})

	register(&mcp.Tool{Name: "get_execution_status", Description: "Check the status of a requested execution",
		InputSchema: objSchema(
			prop{"execution_id", "string", "Execution UUID (from request_execution output)"},
		),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		execID, _ := args["execution_id"].(string)
		if execID == "" {
			return textResult("execution_id required"), nil
		}
		eid, err := uuid.Parse(execID)
		if err != nil {
			// Try finding by exec slug prefix
			var found uuid.UUID
			err2 := pool.QueryRow(ctx, "SELECT entity_id FROM executions WHERE entity_id::text LIKE $1 LIMIT 1", execID+"%").Scan(&found)
			if err2 != nil {
				return textResult(fmt.Sprintf("execution not found: %s", execID)), nil
			}
			eid = found
		}
		return queryRows(ctx, pool, `
			SELECT e.entity_id::text, e.action, e.risk_class, e.status,
			       e.result::text, e.duration_ms, e.started_at::text,
			       e.completed_at::text, e.correlation_id
			FROM executions e
			WHERE e.entity_id = $1`, eid), nil
	})

	register(&mcp.Tool{Name: "get_trend", Description: "Get metric trends for an entity",
		InputSchema: objSchema(
			prop{"entity_id", "string", "Entity slug"},
			prop{"days", "integer", "Look-back window in days (default 7)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["entity_id"].(string)
		days := int(getFloat(args, "days", 7))
		return queryRows(ctx, pool, `
			SELECT metric,
			       ROUND(avg(value)::numeric, 2) AS avg_val,
			       ROUND(stddev(value)::numeric, 2) AS std_val,
			       count(*) AS sample_count,
			       ROUND(regr_slope(value, EXTRACT(EPOCH FROM ts)::numeric)::numeric, 4) AS slope
			FROM metric_samples ms
			JOIN entities e ON e.id = ms.entity_id
			WHERE e.slug = $1 AND ts >= now() - make_interval(days => $2)
			GROUP BY metric
			ORDER BY metric`, slug, days), nil
	})

	register(&mcp.Tool{Name: "get_event_timeline", Description: "Get recent events",
		InputSchema: objSchema(
			prop{"severity", "string", "Filter by severity (info, warn, error)"},
			prop{"entity_slug", "string", "Filter by entity slug"},
			prop{"limit", "integer", "Max rows (default 50)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		limit := int(getFloat(args, "limit", 50))
		return queryRows(ctx, pool, `
			SELECT ev.ts, ev.event_type, ev.severity, ev.actor, e.slug AS entity_slug,
			       ev.message, ev.correlation_id
			FROM events ev
			LEFT JOIN entities e ON e.id = ev.entity_id
			WHERE ($1::text IS NULL OR ev.severity = $1)
			  AND ($2::text IS NULL OR e.slug = $2)
			ORDER BY ev.ts DESC LIMIT $3`,
			nStr(args["severity"]), nStr(args["entity_slug"]), limit), nil
	})

	register(&mcp.Tool{Name: "get_agent_activity", Description: "Agent self-inspection: query agent activity log",
		InputSchema: objSchema(
			prop{"limit", "integer", "Max rows (default 50)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		limit := int(getFloat(args, "limit", 50))
		return queryRows(ctx, pool, `
			SELECT id, ts, agent_id::text, session_id, activity_type, tool_name,
			       entity_id::text, left(input_summary, 200) AS input_summary,
			       left(output_summary, 200) AS output_summary,
			       duration_ms, token_count, success, correlation_id
			FROM agent_activity
			WHERE agent_id = $1
			ORDER BY ts DESC LIMIT $2`, agentID, limit), nil
	})

	// ─── Phase 5: operational MCP tools ──────────────────────────────

	register(&mcp.Tool{Name: "list_lxcs", Description: "List all LXC containers with ID, host, IP, and state",
		InputSchema: objSchema(),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		return queryRows(ctx, pool, `
			SELECT e.slug, e.name, e.attributes->>'pve_id' AS pve_id,
			       e.attributes->>'lan_ip' AS lan_ip,
			       st.health, st.last_check_at
			FROM entities e
			LEFT JOIN entity_status st ON st.entity_id = e.id
			WHERE e.type = 'lxc'
			ORDER BY (e.attributes->>'pve_id')::int`), nil
	})

	register(&mcp.Tool{Name: "ping_service", Description: "Check if a service is reachable via HTTP",
		InputSchema: objSchema(prop{"service_slug", "string", "Service entity slug"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["service_slug"].(string)
		if slug == "" {
			return textResult("service_slug is required"), nil
		}
		rows, err := pool.Query(ctx, `
			SELECT st.health, st.last_check_at, e.attributes->>'url' AS url
			FROM entity_status st
			JOIN entities e ON e.id = st.entity_id
			WHERE e.slug = $1`, slug)
		if err != nil {
			return textResult(fmt.Sprintf("query error: %v", err)), nil
		}
		defer rows.Close()
		if !rows.Next() {
			return textResult(fmt.Sprintf("service not found: %s", slug)), nil
		}
		var health, lastCheck, url string
		rows.Scan(&health, &lastCheck, &url)
		if url == "" {
			url = "(no URL in entity attributes)"
		}
		return textResult(fmt.Sprintf("health=%s last_check=%s url=%s", health, lastCheck, url)), nil
	})

	register(&mcp.Tool{Name: "tail_log", Description: "Get recent log lines from a service via journalctl",
		InputSchema: objSchema(
			prop{"service_slug", "string", "Service entity slug (e.g. lxc:caddy)"},
			prop{"lines", "integer", "Number of lines (default 50)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["service_slug"].(string)
		n := int(getFloat(args, "lines", 50))
		if slug == "" {
			return textResult("service_slug is required"), nil
		}
		host, user, err := resolveHost(ctx, pool, slug)
		if err != nil {
			return textResult(fmt.Sprintf("resolve host: %v", err)), nil
		}
		svc := strings.TrimPrefix(slug, "lxc:")
		out, err := sshExec(ctx, host, user, fmt.Sprintf("journalctl -u %s -n %d --no-pager 2>&1 || true", svc, n))
		if err != nil {
			return textResult(fmt.Sprintf("ssh: %v", err)), nil
		}
		return textResult(out), nil
	})

	register(&mcp.Tool{Name: "get_service_status", Description: "Check systemd service status on a host",
		InputSchema: objSchema(
			prop{"service_slug", "string", "Service entity slug (e.g. lxc:caddy)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["service_slug"].(string)
		if slug == "" {
			return textResult("service_slug is required"), nil
		}
		host, user, err := resolveHost(ctx, pool, slug)
		if err != nil {
			return textResult(fmt.Sprintf("resolve host: %v", err)), nil
		}
		svc := strings.TrimPrefix(slug, "lxc:")
		out, err := sshExec(ctx, host, user,
			fmt.Sprintf("systemctl is-active %s; systemctl is-enabled %s; systemctl show %s -p ActiveEnterTimestamp -p SubState 2>&1 || true", svc, svc, svc))
		if err != nil {
			return textResult(fmt.Sprintf("ssh: %v", err)), nil
		}
		return textResult(out), nil
	})

	register(&mcp.Tool{Name: "get_lxc_state", Description: "Get LXC container resource state from Proxmox host",
		InputSchema: objSchema(
			prop{"lxc_slug", "string", "LXC entity slug (e.g. lxc:caddy)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["lxc_slug"].(string)
		if slug == "" {
			return textResult("lxc_slug is required"), nil
		}
		var pveID string
		err := pool.QueryRow(ctx, "SELECT attributes->>'pve_id' FROM entities WHERE slug = $1", slug).Scan(&pveID)
		if err != nil || pveID == "" {
			return textResult(fmt.Sprintf("LXC not found or missing pve_id: %s", slug)), nil
		}
		// Resolve the Proxmox host — find the host that runs this LXC
		var hostID uuid.UUID
		err = pool.QueryRow(ctx, `
			SELECT t.id FROM entities t
			JOIN relationships r ON r.source_id = t.id
			JOIN entities s ON s.id = r.target_id
			WHERE s.slug = $1 AND r.type = 'hosts' AND r.valid_to IS NULL
			LIMIT 1`, slug).Scan(&hostID)
		if err != nil {
			// Fallback: use the inventory host attribute if no relationship
			var hostSlug string
			err = pool.QueryRow(ctx, "SELECT attributes->>'host' FROM entities WHERE slug = $1", slug).Scan(&hostSlug)
			if err != nil || hostSlug == "" {
				return textResult(fmt.Sprintf("cannot resolve Proxmox host for %s", slug)), nil
			}
			var host, user string
			host, user, err = resolveHost(ctx, pool, "host:"+hostSlug)
			if err != nil {
				return textResult(fmt.Sprintf("resolve: %v", err)), nil
			}
			out, err2 := sshExec(ctx, host, user, fmt.Sprintf("pct status %s --verbose 2>&1 || true", pveID))
			if err2 != nil {
				return textResult(fmt.Sprintf("ssh: %v", err2)), nil
			}
			return textResult(out), nil
		}
		var hostSlug string
		pool.QueryRow(ctx, "SELECT slug FROM entities WHERE id = $1", hostID).Scan(&hostSlug)
		host, user, err := resolveHost(ctx, pool, hostSlug)
		if err != nil {
			return textResult(fmt.Sprintf("resolve host: %v", err)), nil
		}
		out, err := sshExec(ctx, host, user, fmt.Sprintf("pct status %s --verbose 2>&1 || true", pveID))
		if err != nil {
			return textResult(fmt.Sprintf("ssh: %v", err)), nil
		}
		return textResult(out), nil
	})

	// ─── Client introspection tools (plan: client-lifecycle Phase 3) ──

	register(&mcp.Tool{Name: "whoami", Description: "Get the current entity record, peers, and health for a host",
		InputSchema: objSchema(prop{"hostname", "string", "Hostname of the calling machine"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		hostname, _ := args["hostname"].(string)
		if hostname == "" {
			return textResult("error: hostname required"), nil
		}
		slug := "ws:" + hostname
		return queryRows(ctx, pool, `
			SELECT e.slug, e.type, e.name, e.state,
			       COALESCE(st.health, 'unknown') AS health,
			       COALESCE(st.last_check_at::text, '') AS last_check,
			       e.attributes->>'mesh_ip' AS mesh_ip,
			       e.attributes->>'age_pubkey' AS age_pubkey,
			       e.enrolled_at
			FROM entities e
			LEFT JOIN entity_status st ON st.entity_id = e.id
			WHERE e.slug = $1
			ORDER BY e.slug`, slug), nil
	})

	register(&mcp.Tool{Name: "explain", Description: "Compact context card for a service: type, state, health, relations, risk",
		InputSchema: objSchema(prop{"service_slug", "string", "Service entity slug (e.g. service:jellyfin, lxc:caddy)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["service_slug"].(string)
		if slug == "" {
			return textResult("error: service_slug required"), nil
		}
		return queryRows(ctx, pool, `
			SELECT e.slug, e.type, e.name, e.state,
			       COALESCE(st.health, 'unknown') AS health,
			       COALESCE(st.last_check_at::text, '') AS last_check,
			       e.version, e.updated_at,
			       COALESCE(e.attributes::text, '{}') AS attrs
			FROM entities e
			LEFT JOIN entity_status st ON st.entity_id = e.id
			WHERE e.slug = $1`, slug), nil
	})

	register(&mcp.Tool{Name: "preflight", Description: "Risk classification for an action on a service",
		InputSchema: objSchema(
			prop{"service_slug", "string", "Entity slug"},
			prop{"action", "string", "Planned action (restart, deploy, destroy, etc.)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["service_slug"].(string)
		action, _ := args["action"].(string)
		if slug == "" || action == "" {
			return textResult("error: service_slug and action required"), nil
		}
		return queryRows(ctx, pool, `
			SELECT e.slug, e.type, e.state,
			       CASE
			         WHEN $2 IN ('restart', 'logs', 'status') THEN 'reversible_low'
			         WHEN $2 IN ('deploy', 'upgrade', 'configure') THEN 'config_mutation'
			         WHEN $2 IN ('destroy', 'wipe', 'revoke') THEN 'destructive'
			         ELSE 'read_only'
			       END AS risk_class,
			       CASE
			         WHEN $2 IN ('read_only','reversible_low') THEN 'auto-act'
			         WHEN $2 = 'config_mutation' THEN 'operator-approval'
			         ELSE 'operator-approval+confirmation'
			       END AS approval
			FROM entities e WHERE e.slug = $1`, slug, action), nil
	})

	register(&mcp.Tool{Name: "get_change_history", Description: "Last N change-ledger entries for an entity",
		InputSchema: objSchema(
			prop{"entity_slug", "string", "Entity slug"},
			prop{"limit", "integer", "Max entries (default 20)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		slug, _ := args["entity_slug"].(string)
		limit := int(getFloat(args, "limit", 20))
		return queryRows(ctx, pool, `
			SELECT al.timestamp, al.actor_type, al.actor_label,
			       al.action, al.method, al.path,
			       al.details::text AS details
			FROM audit_log al
			JOIN entities e ON e.id = al.entity_id
			WHERE e.slug = $1
			ORDER BY al.timestamp DESC
			LIMIT $2`, slug, limit), nil
	})

	register(&mcp.Tool{Name: "get_state_snapshot", Description: "Last scheduler Observe-pass: fleet health, disk, drift count",
		InputSchema: objSchema(),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		return queryRows(ctx, pool, `
			SELECT e.slug, e.type, e.state,
			       COALESCE(st.health, 'unknown') AS health,
			       COALESCE(st.last_check_at::text, '') AS last_check,
			       COALESCE(st.disk_usage_pct, 0) AS disk_pct,
			       COALESCE(st.drift_count, 0) AS drift_count
			FROM entities e
			LEFT JOIN entity_status st ON st.entity_id = e.id
			ORDER BY st.health, e.slug
			LIMIT 200
		`), nil
	})

	register(&mcp.Tool{Name: "list_my_secrets", Description: "List secrets accessible to this client by public key",
		InputSchema: objSchema(prop{"caller_pubkey", "string", "Age public key of the caller (optional)"}),
	}, func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		args := argsMap(req)
		pubkey, _ := args["caller_pubkey"].(string)
		// Match entities where age_pubkey attribute contains the caller's key.
		query := `
			SELECT e.slug, e.type, e.name,
			       e.attributes->>'age_pubkey' AS age_pubkey
			FROM entities e
			WHERE e.attributes->>'age_pubkey' IS NOT NULL`
		var dbArgs []any
		if pubkey != "" {
			query += ` AND e.attributes->>'age_pubkey' = $1`
			dbArgs = append(dbArgs, pubkey)
		}
		query += ` ORDER BY e.slug LIMIT 100`
		return queryRows(ctx, pool, query, dbArgs...), nil
	})

	return s
}

// withActivityLogging wraps a tool handler to record agent_activity rows.
func withActivityLogging(pool *db.Pool, agentID uuid.UUID, toolName string, next mcp.ToolHandler) mcp.ToolHandler {
	if agentID == uuid.Nil {
		return next
	}
	return func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
		start := time.Now()
		result, err := next(ctx, req)
		duration := int(time.Since(start).Milliseconds())

		// Build input summary (first 500 chars of args)
		inputSummary := ""
		if req != nil && len(req.Params.Arguments) > 0 {
			inputSummary = string(req.Params.Arguments)
		}
		if len(inputSummary) > 500 {
			inputSummary = inputSummary[:500]
		}

		// Build output summary
		outputSummary := ""
		success := err == nil
		if result != nil {
			for _, c := range result.Content {
				if tc, ok := c.(*mcp.TextContent); ok {
					outputSummary = tc.Text
					break
				}
			}
		}
		if err != nil {
			outputSummary = err.Error()
			success = false
		}
		if len(outputSummary) > 500 {
			outputSummary = outputSummary[:500]
		}

		correlationID := uuid.New().String()

		_, logErr := pool.Exec(ctx, `
			INSERT INTO agent_activity
			    (agent_id, activity_type, tool_name, input_summary, output_summary,
			     duration_ms, success, correlation_id)
			VALUES ($1, $2, $3, $4, $5, $6, $7, $8)`,
			agentID, "tool_call", toolName, inputSummary, outputSummary,
			duration, success, correlationID)
		if logErr != nil {
			slog.Warn("mcp: log agent_activity", "error", logErr)
		}

		return result, err
	}
}

// ─── Helpers ──────────────────────────────────────────────────────────

func argsMap(req *mcp.CallToolRequest) map[string]any {
	if req == nil || len(req.Params.Arguments) == 0 {
		return nil
	}
	var m map[string]any
	json.Unmarshal(req.Params.Arguments, &m)
	return m
}

func getFloat(m map[string]any, key string, def float64) float64 {
	if m == nil {
		return def
	}
	switch v := m[key].(type) {
	case float64:
		return v
	case int:
		return float64(v)
	case json.Number:
		f, err := v.Float64()
		if err != nil {
			return def
		}
		return f
	}
	return def
}

func nStr(v any) any {
	if v == nil {
		return nil
	}
	s, _ := v.(string)
	if s == "" {
		return nil
	}
	return s
}

func textResult(s string) *mcp.CallToolResult {
	return &mcp.CallToolResult{
		Content: []mcp.Content{&mcp.TextContent{Text: s}},
	}
}

func queryEntity(ctx context.Context, pool *db.Pool, idOrSlug string) *mcp.CallToolResult {
	var id uuid.UUID
	if u, err := uuid.Parse(idOrSlug); err == nil {
		id = u
	} else {
		pool.QueryRow(ctx, "SELECT id FROM entities WHERE slug = $1", idOrSlug).Scan(&id)
	}
	if id == uuid.Nil {
		return textResult(fmt.Sprintf("entity not found: %s", idOrSlug))
	}
	return queryRows(ctx, pool, `
		SELECT slug, type, name, state, attributes,
		       maintenance_until::text, version, created_at, updated_at
		FROM entities WHERE id = $1`, id)
}

func queryRows(ctx context.Context, pool *db.Pool, query string, args ...any) *mcp.CallToolResult {
	rows, err := pool.Query(ctx, query, args...)
	if err != nil {
		return textResult(fmt.Sprintf("error: %v", err))
	}
	defer rows.Close()

	cols := rows.FieldDescriptions()
	var items []map[string]any
	for rows.Next() {
		vals, err := rows.Values()
		if err != nil {
			continue
		}
		m := make(map[string]any)
		for i, col := range cols {
			m[string(col.Name)] = fmt.Sprintf("%v", vals[i])
		}
		items = append(items, m)
	}
	if err := rows.Err(); err != nil {
		return textResult(fmt.Sprintf("error: %v", err))
	}

	data, _ := json.MarshalIndent(items, "", "  ")
	return textResult(string(data))
}

// ─── SSH helpers ─────────────────────────────────────────────────────────

var (
	sshUser   string
	sshKey    []byte
	sshPool   = make(map[string]*ssh.Client)
	sshPoolMu sync.Mutex
)

func initSSH() {
	if sshUser == "" {
		sshUser = os.Getenv("OIKOS_SSH_USER")
		if sshUser == "" {
			sshUser = "root"
		}
	}
	keyPath := os.Getenv("OIKOS_SSH_KEY_PATH")
	if keyPath == "" {
		keyPath = "/etc/oikos/ssh_key"
	}
	if len(sshKey) == 0 {
		var err error
		sshKey, err = os.ReadFile(keyPath)
		if err != nil {
			slog.Warn("mcp ssh: cannot read key", "path", keyPath, "error", err)
		}
	}
}

func sshExec(ctx context.Context, host, user, command string) (string, error) {
	initSSH()
	if len(sshKey) == 0 {
		return "", fmt.Errorf("no SSH key available")
	}
	if user == "" {
		user = sshUser
	}

	addr := host + ":22"
	signer, err := ssh.ParsePrivateKey(sshKey)
	if err != nil {
		return "", fmt.Errorf("parse key: %w", err)
	}

	cfg := &ssh.ClientConfig{
		User:            user,
		Auth:            []ssh.AuthMethod{ssh.PublicKeys(signer)},
		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
		Timeout:         10 * time.Second,
	}

	client, err := ssh.Dial("tcp", addr, cfg)
	if err != nil {
		return "", fmt.Errorf("dial %s: %w", host, err)
	}
	defer client.Close()

	session, err := client.NewSession()
	if err != nil {
		return "", fmt.Errorf("session: %w", err)
	}
	defer session.Close()

	out, err := session.CombinedOutput(command)
	if err != nil && out == nil {
		return "", fmt.Errorf("exec: %w", err)
	}
	return strings.TrimSpace(string(out)), nil
}

func resolveHost(ctx context.Context, pool *db.Pool, entitySlug string) (hostIP string, sshUser string, err error) {
	var attrs string
	err = pool.QueryRow(ctx, "SELECT attributes::text FROM entities WHERE slug = $1", entitySlug).Scan(&attrs)
	if err != nil {
		return "", "", fmt.Errorf("entity not found: %s", entitySlug)
	}

	var m map[string]interface{}
	if err := json.Unmarshal([]byte(attrs), &m); err != nil {
		return "", "", fmt.Errorf("parse attributes: %w", err)
	}

	if ip, ok := m["lan_ip"].(string); ok && ip != "" {
		return ip, sshUser, nil
	}
	if mesh, ok := m["mesh"].(map[string]interface{}); ok {
		for _, proto := range []string{"netbird", "tailscale"} {
			if p, ok := mesh[proto].(map[string]interface{}); ok {
				if ip, ok := p["ip"].(string); ok && ip != "" {
					return ip, sshUser, nil
				}
			}
		}
	}
	return "", "", fmt.Errorf("no IP found for %s", entitySlug)
}

func createApproval(ctx context.Context, pool *db.Pool, execID, targetID uuid.UUID, action, params, riskClass string) {
	approvalID, _ := uuid.NewV7()
	payload := fmt.Sprintf(`{"action":"%s","params":"%s","execution_id":"%s"}`, action, params, execID)
	pool.Exec(ctx, `
		INSERT INTO approvals (entity_id, subject_entity_id, action, risk_class,
			kind, payload, status, expires_at, created_at)
		VALUES ($1, $2, $3, $4, 'execution', $5::jsonb, 'pending',
			now() + interval '1 hour', now())`,
		approvalID, targetID, action, riskClass, payload)
	pool.Exec(ctx, `UPDATE executions SET approval_id = $2 WHERE entity_id = $1`, execID, approvalID)
}