package db

import (
	"context"
	"encoding/json"
	"time"

	"github.com/dtoro/oikos/internal/adapters/postgres/sqlcgen"
	"github.com/dtoro/oikos/internal/core/domain"
	"github.com/dtoro/oikos/internal/core/ports"
	"github.com/dtoro/oikos/internal/observability"
	"github.com/google/uuid"
)

// GovernanceRepo implements ports.GovernanceStore over the postgres
// pool. The SQL is lifted from the MCP classifyAndGate path (Phase 4
// convergence); fail-open/fail-closed semantics per gate are preserved
// and documented on the port.
type GovernanceRepo struct {
	pool *Pool
}

var _ ports.GovernanceStore = (*GovernanceRepo)(nil)

// NewGovernanceRepo builds the governance read model.
func NewGovernanceRepo(pool *Pool) *GovernanceRepo { return &GovernanceRepo{pool: pool} }

// SessionHasPlan fails open (true) on query error — a transient DB issue
// must not block an otherwise-valid run.
func (g *GovernanceRepo) SessionHasPlan(ctx context.Context, sessionID string) bool {
	if sessionID == "" {
		return true // no session → no gate (direct MCP call from a script)
	}
	var count int
	if err := g.pool.QueryRow(ctx,
		`SELECT COUNT(*) FROM session_plan_steps
		 WHERE session_id = $1 AND status <> 'replaced'`,
		sessionID).Scan(&count); err != nil {
		return true
	}
	return count > 0
}

// AssentWindowActive checks the session-scoped assent window key set by
// chat assent and the approval-decide path.
func (g *GovernanceRepo) AssentWindowActive(ctx context.Context, agentID domain.UUID, sessionID string) bool {
	if agentID == "" || sessionID == "" {
		return false // fail closed
	}
	return g.windowActive(ctx, "assent_window.agent:"+string(agentID)+".session:"+sessionID)
}

// DestructiveWindowActive checks the target+session-scoped destructive
// window key. Key format must match cmd/nomos/store.go's
// openDestructiveWindow — both processes read/write the same rows.
func (g *GovernanceRepo) DestructiveWindowActive(ctx context.Context, agentID domain.UUID, targetSlug, sessionID string) bool {
	if agentID == "" || targetSlug == "" || sessionID == "" {
		return false // fail closed
	}
	return g.windowActive(ctx,
		"destructive_window.agent:"+string(agentID)+".target:"+targetSlug+".session:"+sessionID)
}

func (g *GovernanceRepo) windowActive(ctx context.Context, key string) bool {
	var expiresStr string
	err := g.pool.QueryRow(ctx,
		"SELECT value FROM autonomy_settings WHERE key = $1", key).Scan(&expiresStr)
	if err != nil {
		return false
	}
	expires, err := time.Parse(time.RFC3339, expiresStr)
	if err != nil {
		return false
	}
	return time.Now().UTC().Before(expires)
}

// PendingApprovalCount returns the session's executions at pending_approval.
func (g *GovernanceRepo) PendingApprovalCount(ctx context.Context, sessionID string) int {
	var n int
	if err := g.pool.QueryRow(ctx, `
		SELECT COUNT(*) FROM nomos_plan_executions pe
		JOIN executions ex ON ex.entity_id = pe.execution_id
		WHERE pe.session_id = $1 AND ex.status = 'pending_approval'`,
		sessionID).Scan(&n); err != nil {
		return 0 // fail open for the flood gate: don't block on a flake
	}
	return n
}

// PendingDuplicate returns the newest identical pending execution on the
// target, if any.
func (g *GovernanceRepo) PendingDuplicate(ctx context.Context, targetID domain.UUID, action string) (domain.UUID, bool) {
	var existingID string
	err := g.pool.QueryRow(ctx, `
		SELECT e.id::text FROM entities e
		JOIN executions ex ON ex.entity_id = e.id
		WHERE e.type = 'execution' AND ex.target_entity_id = $1
		  AND ex.action = $2 AND ex.status = 'pending_approval'
		ORDER BY e.created_at DESC LIMIT 1`,
		mustUUID(targetID), action).Scan(&existingID)
	if err != nil || existingID == "" {
		return "", false
	}
	return domain.UUID(existingID), true
}

// EntityAttributes loads one entity's attributes map.
func (g *GovernanceRepo) EntityAttributes(ctx context.Context, targetID domain.UUID) (map[string]any, error) {
	var rawAttrs []byte
	if err := g.pool.QueryRow(ctx,
		`SELECT attributes FROM entities WHERE id = $1`, mustUUID(targetID)).Scan(&rawAttrs); err != nil {
		return nil, err
	}
	var attrs map[string]any
	if err := json.Unmarshal(rawAttrs, &attrs); err != nil {
		return nil, err
	}
	return attrs, nil
}

// ResolveProxmoxHostSlug resolves the Proxmox host owning a guest slug
// (refusal-hint input for host-only commands). Removed — importing
// internal/remote from the postgres adapter forms an import cycle; the
// hint is wired at composition time via PolicyService.HostHint instead.

// ExecRunRepo implements ports.ExecutionRecorder over the postgres
// pool: the write half of the run-submission lifecycle, lifted from the
// MCP classifyAndGate / autoRun / createApproval /
// markSessionAwaitingApproval paths (Phase 4 convergence).
type ExecRunRepo struct {
	pool *Pool
}

var _ ports.ExecutionRecorder = (*ExecRunRepo)(nil)

// NewExecRunRepo builds the recorder.
func NewExecRunRepo(pool *Pool) *ExecRunRepo { return &ExecRunRepo{pool: pool} }

// CreateRun writes the execution entity + row, graph edges, session
// link, classification row, and audit entry.
func (r *ExecRunRepo) CreateRun(ctx context.Context, in ports.CreateRunInput) error {
	id := mustUUID(in.ExecutionID)
	execName := "run on " + in.TargetSlug + " (" + id.String() + ")"
	execSlug := "exec:" + in.TargetSlug + ":" + id.String()
	if _, err := r.pool.Exec(ctx,
		`INSERT INTO entities (id, slug, type, name, attributes) VALUES ($1, $2, 'execution', $3, '{}')`,
		id, execSlug, execName); err != nil {
		return err
	}
	if _, err := r.pool.Exec(ctx,
		`INSERT INTO executions (entity_id, target_entity_id, action, risk_class, status, correlation_id, agent_id)
		 VALUES ($1, $2, $3, $4, 'running', $5, $6) ON CONFLICT DO NOTHING`,
		id, mustUUID(in.TargetID), in.Action, in.RiskClass, in.CorrelationID, agentUUID(in.AgentID)); err != nil {
		return err
	}
	if _, err := r.pool.Exec(ctx, `
		INSERT INTO relationships (source_id, target_id, type, attributes, valid_from)
		SELECT $1, $2, 'targets', '{"by":"nomos"}'::jsonb, now()
		WHERE NOT EXISTS (
			SELECT 1 FROM relationships
			WHERE source_id = $1 AND target_id = $2 AND type = 'targets' AND valid_to IS NULL)`,
		id, mustUUID(in.TargetID)); err != nil {
		return err
	}

	auditSessionID := sessionUUID(in.SessionID)
	if in.SessionID != "" {
		if _, err := r.pool.Exec(ctx, `
			INSERT INTO relationships (source_id, target_id, type, attributes, valid_from)
			SELECT t.id, $1, 'involves', '{"by":"nomos"}'::jsonb, now()
			FROM entities t WHERE t.slug = $2
			AND NOT EXISTS (
				SELECT 1 FROM relationships
				WHERE source_id = t.id AND target_id = $1 AND type = 'involves' AND valid_to IS NULL)`,
			id, "task:"+in.SessionID); err != nil {
			return err
		}
		// Link execution to session for auto-continuation.
		if auditSessionID != nil {
			if _, err := r.pool.Exec(ctx, `
				INSERT INTO nomos_plan_executions (execution_id, session_id)
				VALUES ($1, $2) ON CONFLICT (execution_id) DO NOTHING`, id, *auditSessionID); err != nil {
				return err
			}
		}
	}

	// Auto-classify: write the classification decision.
	classID, err := uuid.NewV7()
	if err != nil {
		return err
	}
	if _, err := r.pool.Exec(ctx,
		`INSERT INTO entities (id, slug, type, name, attributes) VALUES ($1, $2, 'classification', $3, '{}')`,
		classID, "classification:"+classID.String(), "classification for "+execSlug); err != nil {
		return err
	}
	if _, err := r.pool.Exec(ctx,
		`INSERT INTO classifications (entity_id, action, risk_class, route, reasoning, correlation_id)
		 VALUES ($1, $2, $3, $4, $5, $6)`,
		classID, in.Action, in.RiskClass, in.Route, string(in.ClassReasoning), in.CorrelationID); err != nil {
		return err
	}
	if _, err := r.pool.Exec(ctx,
		`UPDATE executions SET classification_id = $2 WHERE entity_id = $1`, id, classID); err != nil {
		return err
	}
	if _, err := r.pool.Exec(ctx, `
		INSERT INTO relationships (source_id, target_id, type, attributes, valid_from)
		SELECT $1, $2, 'precedes', '{"by":"nomos"}'::jsonb, now()
		WHERE NOT EXISTS (
			SELECT 1 FROM relationships
			WHERE source_id = $1 AND target_id = $2 AND type = 'precedes' AND valid_to IS NULL)`,
		classID, id); err != nil {
		return err
	}

	// Audit the run request (every run, auto or queued).
	q := sqlcgen.New(r.pool)
	return observability.Audit(ctx, q, "agent", "nomos", "run",
		&id, "POST", "/mcp", in.CorrelationID, auditSessionID, map[string]any{
			"command": in.Command, "target": in.TargetSlug,
			"risk_class": in.RiskClass, "purpose": in.Purpose,
		})
}

// MarkRunning stamps status + started_at now.
func (r *ExecRunRepo) MarkRunning(ctx context.Context, id domain.UUID) error {
	_, err := r.pool.Exec(ctx,
		`UPDATE executions SET status='running', started_at=$2 WHERE entity_id=$1`,
		mustUUID(id), time.Now())
	return err
}

// Finalize stamps the terminal status, result payload, duration, and
// completion time.
func (r *ExecRunRepo) Finalize(ctx context.Context, in ports.FinalizeExecutionInput) error {
	_, err := r.pool.Exec(ctx,
		`UPDATE executions SET status=$2, result=$3::jsonb, duration_ms=$4,
		        started_at=$5, completed_at=now()
		 WHERE entity_id=$1`,
		mustUUID(in.ExecutionID), in.Status, string(in.Result),
		int(time.Since(in.StartedAt).Milliseconds()), in.StartedAt)
	return err
}

// QueueApproval creates the approval row, flips the execution to
// pending_approval, emits approval.created, and marks the session
// awaiting_input.
func (r *ExecRunRepo) QueueApproval(ctx context.Context, in ports.QueueApprovalInput) error {
	id := mustUUID(in.ExecutionID)
	payload, _ := json.Marshal(map[string]any{"action": in.Action, "params": in.Params, "execution_id": in.ExecutionID})
	// approvals.entity_id is PK + FK to entities(id). Reuse the
	// execution's entity so the FK is satisfied — a fresh UUID here has no
	// matching entities row and the INSERT silently fails, orphaning the
	// execution (one execution maps to at most one approval, so the 1:1
	// identity holds).
	subject := mustUUID(in.TargetID)
	if err := sqlcgen.New(r.pool).InsertApproval(ctx, sqlcgen.InsertApprovalParams{
		EntityID:        id,
		SubjectEntityID: &subject,
		Action:          in.Action,
		RiskClass:       in.RiskClass,
		Kind:            "execution",
		Payload:         payload,
		TokenHash:       nil,
		ExpiresAt:       time.Now().Add(time.Hour),
	}); err != nil {
		return err
	}
	if _, err := r.pool.Exec(ctx,
		`UPDATE executions SET approval_id = $1, status='pending_approval', risk_class=$2 WHERE entity_id = $1`,
		id, in.RiskClass); err != nil {
		return err
	}

	// Operator-facing SSE event: a gated action now awaits a decision.
	q := sqlcgen.New(r.pool)
	_ = observability.Event(ctx, q, "approval.created", &id, "warning", "mcp", "",
		map[string]any{"action": in.Action, "params": in.Params, "risk_class": in.RiskClass})

	// Flip the session to awaiting_input so boards and the idle sweep see
	// the task as blocked on the operator, not silently working. No-op for
	// direct MCP calls with no nomos session.
	if in.SessionID == "" || in.SessionID == "ephemeral" {
		return nil
	}
	tag, err := r.pool.Exec(ctx, `
		UPDATE agent_sessions SET status = 'awaiting_input', last_active_at = now()
		WHERE id = $1 AND status IN ('active', 'planning', 'executing')`, in.SessionID)
	if err != nil || tag.RowsAffected() == 0 {
		return nil
	}
	var taskEntID *uuid.UUID
	var e uuid.UUID
	if qerr := r.pool.QueryRow(ctx, `SELECT entity_id FROM agent_sessions WHERE id = $1`, in.SessionID).Scan(&e); qerr == nil && e != uuid.Nil {
		taskEntID = &e
	}
	return observability.Event(ctx, q, "task.status", taskEntID, "info", "nomos", in.SessionID,
		map[string]any{"status": "awaiting_input", "reason": "execution_pending_approval"})
}

// agentUUID maps a domain agent id to pg uuid (nil-safe).
func agentUUID(id domain.UUID) any {
	if id == "" {
		return nil
	}
	return mustUUID(id)
}

// sessionUUID parses a session id for audit linkage; nil when absent or
// ephemeral.
func sessionUUID(sessionID string) *uuid.UUID {
	if sessionID == "" || sessionID == "ephemeral" {
		return nil
	}
	sid, err := uuid.Parse(sessionID)
	if err != nil {
		return nil
	}
	return &sid
}