package app

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"github.com/dtoro/oikos/internal/core/domain"
	"github.com/dtoro/oikos/internal/core/ports"
	"github.com/dtoro/oikos/internal/safego"
	"github.com/google/uuid"
)

// ExecutionService is the run-submission use-case: gate via PolicyService,
// record the submission, then either execute immediately over the
// CommandExecutor port or queue an operator approval. Both entry paths
// (MCP `run`/`docker_exec` tools, and any future REST surface) converge
// here — one policy, one audit trail (plan §4.A).
type ExecutionService struct {
	policy   *PolicyService
	exec     ports.CommandExecutor
	resolver ports.TargetResolver
	recorder ports.ExecutionRecorder
}

// NewExecutionService wires the service.
func NewExecutionService(
	policy *PolicyService,
	exec ports.CommandExecutor,
	resolver ports.TargetResolver,
	recorder ports.ExecutionRecorder,
) *ExecutionService {
	return &ExecutionService{policy: policy, exec: exec, resolver: resolver, recorder: recorder}
}

// ExecutionSubmitCmd is one `run` submission.
type ExecutionSubmitCmd struct {
	AgentID      domain.UUID
	TargetID     domain.UUID
	TargetSlug   string
	Command      string
	Purpose      string
	DeclaredRisk string
	SessionID    string
	// Async, when true and the decision is auto-run, dispatches the
	// execution in a background goroutine and returns immediately with
	// AsyncStarted — for long-running commands that would exceed the
	// caller's round-trip timeout. Set it via PolicyService's
	// IsLongRunningCommand at the caller, or directly.
	Async bool
	// SinkFactory builds the output stream sink for the execution once
	// its id and correlation id are known (the adapter wires its log
	// streaming here; nil means no streaming).
	SinkFactory func(ctx context.Context, executionID domain.UUID, correlationID string) (sink func(stream string, chunk []byte), flush func())
}

// ExecutionSubmitResult is the submission outcome for the calling
// adapter to render.
type ExecutionSubmitResult struct {
	Decision PolicyDecision
	// ExecutionID is set for every non-refused submission (auto and
	// queue paths) — the ledger id to poll with get_execution_status.
	ExecutionID domain.UUID
	// Output/Error carry the command result when it ran synchronously.
	Output string
	Err    error
	// AsyncStarted reports the execution was dispatched in the
	// background.
	AsyncStarted bool
}

// Submit gates, records, and dispatches one command. Refusals return the
// agent-facing message without recording anything; auto-run paths record
// the submission then execute; queue paths record and create the
// approval ask.
func (s *ExecutionService) Submit(ctx context.Context, cmd ExecutionSubmitCmd) ExecutionSubmitResult {
	decision := s.policy.Decide(ctx, PolicySubmitInput{
		AgentID:      cmd.AgentID,
		TargetID:     cmd.TargetID,
		TargetSlug:   cmd.TargetSlug,
		Command:      cmd.Command,
		Purpose:      cmd.Purpose,
		DeclaredRisk: cmd.DeclaredRisk,
		SessionID:    cmd.SessionID,
	})
	if decision.Action == DecisionRefuse {
		return ExecutionSubmitResult{Decision: decision}
	}

	execID, err := uuid.NewV7()
	if err != nil {
		return ExecutionSubmitResult{Decision: decision, Err: err}
	}

	// Correlate the execution to the chat session that asked for it —
	// execution events carry correlation_id, so the UI can match them to
	// the session on screen. Fresh random id when there is no session.
	correlationID := cmd.SessionID
	if correlationID == "" || correlationID == "ephemeral" {
		correlationID = uuid.New().String()
	}

	reason, _ := json.Marshal(map[string]string{
		"command": cmd.Command, "purpose": cmd.Purpose,
		"target": cmd.TargetSlug, "declared_risk": cmd.DeclaredRisk,
	})
	if err := s.recorder.CreateRun(ctx, ports.CreateRunInput{
		ExecutionID:    domain.UUID(execID.String()),
		TargetID:       cmd.TargetID,
		TargetSlug:     cmd.TargetSlug,
		AgentID:        cmd.AgentID,
		SessionID:      cmd.SessionID,
		Command:        cmd.Command,
		Purpose:        cmd.Purpose,
		Action:         RunActionParams(cmd.Command, cmd.Purpose),
		RiskClass:      decision.RiskClass,
		Route:          decision.Route,
		ClassReasoning: reason,
		CorrelationID:  correlationID,
	}); err != nil {
		return ExecutionSubmitResult{Decision: decision, Err: fmt.Errorf("record execution: %w", err)}
	}

	execUUID := domain.UUID(execID.String())

	// Build the streaming sink now that the execution id is known.
	var sink func(string, []byte)
	var flush func()
	if cmd.SinkFactory != nil {
		sink, flush = cmd.SinkFactory(ctx, execUUID, correlationID)
	}

	switch decision.Action {
	case DecisionQueue:
		params, _ := json.Marshal(map[string]string{"command": cmd.Command, "purpose": cmd.Purpose})
		if err := s.recorder.QueueApproval(ctx, ports.QueueApprovalInput{
			ExecutionID: execUUID,
			TargetID:    cmd.TargetID,
			TargetSlug:  cmd.TargetSlug,
			Action:      "run",
			Params:      string(params),
			RiskClass:   decision.RiskClass,
			SessionID:   cmd.SessionID,
		}); err != nil {
			return ExecutionSubmitResult{Decision: decision, ExecutionID: execUUID, Err: fmt.Errorf("queue approval: %w", err)}
		}
		return ExecutionSubmitResult{Decision: decision, ExecutionID: execUUID}

	case DecisionAuto:
		if cmd.Async {
			safego.Go("execution:async-run", func() {
				// Result surfaces via the ledger (get_execution_status);
				// the handler already returned "started".
				_, _ = s.dispatch(context.Background(), execUUID, cmd.TargetSlug, cmd.Command, sink, flush)
			})
			return ExecutionSubmitResult{Decision: decision, ExecutionID: execUUID, AsyncStarted: true}
		}
		out, xerr := s.dispatch(ctx, execUUID, cmd.TargetSlug, cmd.Command, sink, flush)
		return ExecutionSubmitResult{Decision: decision, ExecutionID: execUUID, Output: out, Err: xerr}
	}

	return ExecutionSubmitResult{Decision: decision, ExecutionID: execUUID, Err: fmt.Errorf("unknown decision action %q", decision.Action)}
}

// dispatch resolves the target, marks the execution running, executes
// with streaming, and finalizes with full timing. Shared by the sync and
// async auto-run paths.
func (s *ExecutionService) dispatch(ctx context.Context, execID domain.UUID, targetSlug, command string, sink func(string, []byte), flush func()) (string, error) {
	startedAt := time.Now()
	if err := s.recorder.MarkRunning(ctx, execID); err != nil {
		slog.Error("execution: mark running", "error", err, "execution_id", execID)
	}

	target, err := s.resolver.ResolveExecTarget(ctx, targetSlug)
	if err != nil {
		s.finalize(ctx, execID, "failed", jsonErrBytes("%s", err.Error()), startedAt)
		return "", err
	}

	res := s.exec.Run(ctx, target, command, ports.ExecOpts{Sink: sink})
	if flush != nil {
		flush()
	}
	if res.Err != nil {
		s.finalize(ctx, execID, "failed", jsonErrBytes("%s: %s", res.Err.Error(), res.Output), startedAt)
		return res.Output, res.Err
	}
	s.finalize(ctx, execID, "completed", jsonOutBytes(res.Output), startedAt)
	return res.Output, nil
}

func (s *ExecutionService) finalize(ctx context.Context, execID domain.UUID, status string, result []byte, startedAt time.Time) {
	if err := s.recorder.Finalize(ctx, ports.FinalizeExecutionInput{
		ExecutionID: execID, Status: status, Result: result, StartedAt: startedAt,
	}); err != nil {
		slog.Error("execution: finalize", "error", err, "execution_id", execID)
	}
}

// DispatchQueued runs a previously-recorded queued execution (status
// 'proposed' or 'approved') over the CommandExecutor port. The command is
// derived from the execution's action column the same way the legacy worker
// did: "action_name:{json_params}" extracts params["command"], else the
// action string is the raw command. Used by the execworker poller adapter.
func (s *ExecutionService) DispatchQueued(ctx context.Context, execID domain.UUID, targetSlug, action string) (string, error) {
	return s.dispatch(ctx, execID, targetSlug, queuedCommand(action), nil, nil)
}

// queuedCommand extracts the actual shell command from an execution's action
// column. Format: "action_name:{json_params}" → params["command"]; otherwise
// the action string is itself the raw command.
func queuedCommand(action string) string {
	if idx := strings.Index(action, ":"); idx > 0 && idx < len(action)-1 {
		rawParams := action[idx+1:]
		var params map[string]any
		if json.Unmarshal([]byte(rawParams), &params) == nil {
			if c, ok := params["command"].(string); ok && c != "" {
				return c
			}
		}
	}
	return action
}

func jsonOutBytes(out string) []byte {
	b, _ := json.Marshal(map[string]any{"output": out})
	return b
}

func jsonErrBytes(format string, args ...any) []byte {
	b, _ := json.Marshal(map[string]any{"error": fmt.Sprintf(format, args...)})
	return b
}