package worker

import (
	"context"
	"fmt"
	"strings"
	"time"

	"github.com/orchard9/rdev/internal/domain"
	"github.com/orchard9/rdev/internal/logging"
	"github.com/orchard9/rdev/internal/port"
)

// Build event type constants for SSE streaming.
const (
	BuildEventStarted    = "build.started"
	BuildEventOutput     = "build.output"
	BuildEventCompleted  = "build.completed"
	BuildEventFailed     = "build.failed"
	BuildEventToolUse    = "build.tool_use"
	BuildEventToolResult = "build.tool_result"
	BuildEventError      = "build.error"
)

// BuildExecutor handles WorkTaskTypeBuild tasks.
// It translates BuildSpec fields from the work task's Spec map into an
// AgentRequest, executes via a CodeAgent, and returns a BuildResult.
type BuildExecutor struct {
	agentRegistry  port.CodeAgentRegistry
	podGitOps      *PodGitOperations    // Post-build git operations (runs in pod)
	streams        port.StreamPublisher // SSE stream publisher for real-time events
	defaultPodName string               // Default claudebox pod for agent execution
	namespace      string               // Kubernetes namespace for the pod
}

// BuildExecutorConfig holds configuration for the build executor.
type BuildExecutorConfig struct {
	DefaultPodName string // Default pod to execute Claude Code in (e.g., "claudebox-0")
	Namespace      string // Kubernetes namespace (e.g., "rdev")
}

// NewBuildExecutor creates a new build executor.
func NewBuildExecutor(
	agentRegistry port.CodeAgentRegistry,
	podGitOps *PodGitOperations,
	streams port.StreamPublisher,
	cfg *BuildExecutorConfig,
) *BuildExecutor {
	if cfg == nil {
		cfg = &BuildExecutorConfig{
			DefaultPodName: "claudebox-0",
			Namespace:      "rdev",
		}
	}
	return &BuildExecutor{
		agentRegistry:  agentRegistry,
		podGitOps:      podGitOps,
		streams:        streams,
		defaultPodName: cfg.DefaultPodName,
		namespace:      cfg.Namespace,
	}
}

// Execute runs a build task by translating its spec into an agent call.
func (b *BuildExecutor) Execute(ctx context.Context, task *domain.WorkTask) *domain.BuildResult {
	log := logging.FromContext(ctx).WithWorker("build-executor")
	start := time.Now()
	streamID := task.ID // Use task ID as stream ID for SSE

	// Publish BuildEventStarted event
	b.publishEvent(streamID, BuildEventStarted, map[string]any{
		"task_id":    task.ID,
		"project_id": task.ProjectID,
		"started_at": start.Format(time.RFC3339),
	})

	spec, err := b.parseSpec(task.Spec)
	if err != nil {
		b.publishEvent(streamID, BuildEventFailed, map[string]any{
			"task_id": task.ID,
			"error":   fmt.Sprintf("invalid build spec: %v", err),
		})
		return &domain.BuildResult{
			Success:    false,
			Error:      fmt.Sprintf("invalid build spec: %v", err),
			DurationMs: time.Since(start).Milliseconds(),
		}
	}

	// Working directory in the pod where the project repo is cloned
	workDir := "/workspace"

	// Get a code agent
	agent := b.agentRegistry.Default()
	if agent == nil {
		return &domain.BuildResult{
			Success:    false,
			Error:      "no code agent available",
			DurationMs: time.Since(start).Milliseconds(),
		}
	}

	// Determine which pod to execute in (from task spec or default)
	podName, _ := task.Spec["pod_name"].(string)
	if podName == "" {
		podName = b.defaultPodName
	}

	// Clone or update the git repository if git operations are needed.
	// This ensures the workspace is a valid git repo before the agent runs.
	if (spec.AutoCommit || spec.AutoPush) && b.podGitOps != nil {
		if spec.GitCloneURL == "" {
			b.publishEvent(streamID, BuildEventFailed, map[string]any{
				"task_id": task.ID,
				"error":   "git_clone_url is required when auto_commit or auto_push is enabled",
			})
			return &domain.BuildResult{
				Success:    false,
				Error:      "git_clone_url is required when auto_commit or auto_push is enabled",
				DurationMs: time.Since(start).Milliseconds(),
			}
		}

		log.Info("ensuring git repository is ready",
			"task_id", task.ID,
			"pod", podName,
			"workDir", workDir,
		)

		cloneResult := b.podGitOps.CloneRepo(ctx, podName, workDir, spec.GitCloneURL)
		if cloneResult.Error != nil {
			b.publishEvent(streamID, BuildEventFailed, map[string]any{
				"task_id": task.ID,
				"error":   fmt.Sprintf("git clone failed: %v", cloneResult.Error),
			})
			return &domain.BuildResult{
				Success:    false,
				Error:      fmt.Sprintf("git clone failed: %v", cloneResult.Error),
				DurationMs: time.Since(start).Milliseconds(),
			}
		}

		if cloneResult.Cloned {
			b.publishEvent(streamID, BuildEventOutput, map[string]any{
				"content": fmt.Sprintf("Cloned repository to %s", workDir),
			})
		}

		// Reset to main to ensure clean workspace state.
		// Worker pods may be left on a feature branch from a previous task.
		if err := b.podGitOps.ResetToMain(ctx, podName, workDir); err != nil {
			log.Warn("failed to reset workspace to main, continuing",
				"task_id", task.ID,
				logging.FieldError, err,
			)
		}
	}

	// Build the agent request with pod metadata for Claude Code adapter
	agentReq := &domain.AgentRequest{
		Prompt:     spec.Prompt,
		ProjectID:  domain.ProjectID(task.ProjectID),
		WorkingDir: workDir,
		Timeout:    10 * time.Minute,
		Metadata: map[string]string{
			"pod_name":  podName,
			"namespace": b.namespace,
		},
	}

	// Collect output with a size cap to prevent OOM on verbose builds.
	const maxOutputSize = 1 << 20 // 1MB
	var outputBuilder strings.Builder

	log.Info("executing build via agent",
		"task_id", task.ID,
		"project_id", task.ProjectID,
		"agent", agent.Name(),
		"work_dir", workDir,
	)

	// Execute the agent
	agentResult, err := agent.Execute(ctx, agentReq, func(event domain.AgentEvent) {
		// Publish all agent events to the SSE stream
		eventType := BuildEventOutput
		switch event.Type {
		case domain.AgentEventToolUse:
			eventType = BuildEventToolUse
		case domain.AgentEventToolResult:
			eventType = BuildEventToolResult
		case domain.AgentEventError:
			eventType = BuildEventError
		}
		b.publishEvent(streamID, eventType, map[string]any{
			"content":   event.Content,
			"stream":    event.Stream,
			"tool_name": event.ToolName,
		})

		// Also buffer output for final result
		if event.Type == domain.AgentEventOutput || event.Type == domain.AgentEventError {
			if outputBuilder.Len() >= maxOutputSize {
				return // Output cap reached, discard further output
			}
			if outputBuilder.Len() > 0 {
				outputBuilder.WriteString("\n")
			}
			remaining := maxOutputSize - outputBuilder.Len()
			if len(event.Content) > remaining {
				outputBuilder.WriteString(event.Content[:remaining])
				outputBuilder.WriteString("\n... [output truncated at 1MB]")
			} else {
				outputBuilder.WriteString(event.Content)
			}
		}
	})

	if err != nil {
		b.publishEvent(streamID, BuildEventFailed, map[string]any{
			"task_id":     task.ID,
			"error":       fmt.Sprintf("agent execution failed: %v", err),
			"duration_ms": time.Since(start).Milliseconds(),
		})
		b.closeStream(ctx, streamID)
		return &domain.BuildResult{
			Success:    false,
			Error:      fmt.Sprintf("agent execution failed: %v", err),
			Output:     outputBuilder.String(),
			DurationMs: time.Since(start).Milliseconds(),
		}
	}

	// Use streamed output, but fall back to agent's captured output if streaming missed it
	output := outputBuilder.String()
	if output == "" && agentResult.FinalOutput != "" {
		output = agentResult.FinalOutput
	}

	result := &domain.BuildResult{
		Success:    agentResult.Success(),
		Output:     output,
		DurationMs: time.Since(start).Milliseconds(),
		Artifacts:  make(map[string]string),
	}

	// Include SDLC context in artifacts for callback routing
	if spec.SDLCContext != nil {
		if spec.SDLCContext.Feature != "" {
			result.Artifacts["sdlc_feature"] = spec.SDLCContext.Feature
		}
		if spec.SDLCContext.ArtifactType != "" {
			result.Artifacts["sdlc_artifact_type"] = spec.SDLCContext.ArtifactType
		}
		if spec.SDLCContext.TaskID != "" {
			result.Artifacts["sdlc_task_id"] = spec.SDLCContext.TaskID
		}
	}

	if !agentResult.Success() {
		errMsg := "agent returned non-zero exit code"
		if agentResult.Error != nil {
			errMsg = agentResult.Error.Error()
		}
		result.Error = errMsg
	}

	// Post-build git operations: commit and push changes programmatically.
	// This is deterministic - we don't rely on the LLM to run git commands.
	if result.Success && spec.AutoCommit && b.podGitOps != nil {
		commitMsg := fmt.Sprintf("build: %s", truncate(spec.Prompt, 72))
		gitResult := b.podGitOps.CommitAndPush(ctx, podName, workDir, commitMsg, spec.AutoPush)

		if gitResult.Error != nil {
			log.Warn("post-build git operations failed",
				"task_id", task.ID,
				"error", gitResult.Error,
			)
			result.Success = false
			result.Error = fmt.Sprintf("build succeeded but git operations failed: %v", gitResult.Error)
		} else if gitResult.HasChanges {
			result.CommitSHA = gitResult.CommitSHA
			result.FilesChanged = gitResult.FilesChanged
			log.Info("post-build git operations completed",
				"task_id", task.ID,
				"commit", gitResult.CommitSHA,
				"files", len(gitResult.FilesChanged),
				"pushed", gitResult.Pushed,
			)
		} else {
			log.Info("no changes to commit after build",
				"task_id", task.ID,
			)
		}
	}

	// Publish completion event
	if result.Success {
		b.publishEvent(streamID, BuildEventCompleted, map[string]any{
			"task_id":       task.ID,
			"success":       true,
			"commit_sha":    result.CommitSHA,
			"files_changed": result.FilesChanged,
			"duration_ms":   result.DurationMs,
		})
	} else {
		b.publishEvent(streamID, BuildEventFailed, map[string]any{
			"task_id":     task.ID,
			"error":       result.Error,
			"duration_ms": result.DurationMs,
		})
	}
	b.closeStream(ctx, streamID)

	return result
}

// publishEvent publishes an event to the SSE stream if a stream publisher is configured.
func (b *BuildExecutor) publishEvent(streamID, eventType string, data map[string]any) {
	if b.streams == nil {
		return
	}
	b.streams.Publish(streamID, port.StreamEvent{
		Type: eventType,
		Data: data,
	})
}

// streamCloseDelay is the time to wait before closing a stream after build completion.
// This allows SSE clients to receive final events before the stream is closed.
const streamCloseDelay = 5 * time.Second

// closeStream closes the stream after a delay to allow clients to receive final events.
// The close is context-aware and respects cancellation.
func (b *BuildExecutor) closeStream(ctx context.Context, streamID string) {
	if b.streams == nil {
		return
	}
	// Close stream after a short delay to ensure final events are delivered.
	// Use a goroutine with context awareness to avoid race conditions.
	go func() {
		select {
		case <-ctx.Done():
			// Context cancelled, close immediately
			b.streams.Close(streamID)
		case <-time.After(streamCloseDelay):
			b.streams.Close(streamID)
		}
	}()
}

// parsedBuildSpec holds typed fields extracted from the task spec map.
type parsedBuildSpec struct {
	Prompt      string
	AutoCommit  bool
	AutoPush    bool
	GitCloneURL string
	// SDLCContext holds SDLC-specific context for callback routing.
	SDLCContext *sdlcContext
}

// sdlcContext holds SDLC-specific context extracted from the task spec.
type sdlcContext struct {
	Feature      string
	ArtifactType string
	TaskID       string
}

// parseSpec extracts typed BuildSpec fields from the generic map[string]any.
func (b *BuildExecutor) parseSpec(spec map[string]any) (*parsedBuildSpec, error) {
	prompt, _ := spec["prompt"].(string)
	if prompt == "" {
		return nil, fmt.Errorf("prompt is required")
	}

	autoCommit, _ := spec["auto_commit"].(bool)
	autoPush, _ := spec["auto_push"].(bool)
	gitCloneURL, _ := spec["git_clone_url"].(string)

	parsed := &parsedBuildSpec{
		Prompt:      prompt,
		AutoCommit:  autoCommit,
		AutoPush:    autoPush,
		GitCloneURL: gitCloneURL,
	}

	// Extract SDLC context if present
	if sdlcCtx, ok := spec["sdlc_context"].(map[string]any); ok {
		parsed.SDLCContext = &sdlcContext{
			Feature:      stringFromMap(sdlcCtx, "feature"),
			ArtifactType: stringFromMap(sdlcCtx, "artifact_type"),
			TaskID:       stringFromMap(sdlcCtx, "task_id"),
		}
	}

	return parsed, nil
}

// stringFromMap safely extracts a string from a map[string]any.
func stringFromMap(m map[string]any, key string) string {
	if v, ok := m[key].(string); ok {
		return v
	}
	return ""
}

// truncate shortens a string to maxLen, adding "..." if truncated.
func truncate(s string, maxLen int) string {
	if len(s) <= maxLen {
		return s
	}
	if maxLen <= 3 {
		return s[:maxLen]
	}
	return s[:maxLen-3] + "..."
}