package worker

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

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

// 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
	gitOps        *GitOperations
	logger        *slog.Logger
}

// NewBuildExecutor creates a new build executor.
func NewBuildExecutor(
	agentRegistry port.CodeAgentRegistry,
	gitOps *GitOperations,
	logger *slog.Logger,
) *BuildExecutor {
	if logger == nil {
		logger = slog.Default()
	}
	return &BuildExecutor{
		agentRegistry: agentRegistry,
		gitOps:        gitOps,
		logger:        logger.With("component", "build-executor"),
	}
}

// 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 {
	start := time.Now()

	spec, err := b.parseSpec(task.Spec)
	if err != nil {
		return &domain.BuildResult{
			Success:    false,
			Error:      fmt.Sprintf("invalid build spec: %v", err),
			DurationMs: time.Since(start).Milliseconds(),
		}
	}

	// Determine working directory
	workDir := "/workspace"

	// Clone repo if git URL is provided in the spec
	gitURL, _ := task.Spec["git_url"].(string)
	if gitURL != "" && b.gitOps != nil {
		cloneDir, cleanup, err := b.gitOps.CloneToTemp(ctx, gitURL)
		if err != nil {
			return &domain.BuildResult{
				Success:    false,
				Error:      fmt.Sprintf("git clone failed: %v", err),
				DurationMs: time.Since(start).Milliseconds(),
			}
		}
		defer cleanup()
		workDir = cloneDir
	}

	// 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(),
		}
	}

	// Build the agent request
	agentReq := &domain.AgentRequest{
		Prompt:     spec.Prompt,
		ProjectID:  domain.ProjectID(task.ProjectID),
		WorkingDir: workDir,
		Timeout:    10 * time.Minute,
	}

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

	b.logger.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) {
		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 {
		return &domain.BuildResult{
			Success:    false,
			Error:      fmt.Sprintf("agent execution failed: %v", err),
			Output:     outputBuilder.String(),
			DurationMs: time.Since(start).Milliseconds(),
		}
	}

	result := &domain.BuildResult{
		Success:    agentResult.Success(),
		Output:     outputBuilder.String(),
		DurationMs: time.Since(start).Milliseconds(),
	}

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

	// Handle git commit/push if requested
	if result.Success && b.gitOps != nil && gitURL != "" {
		if spec.AutoCommit {
			commitMsg := fmt.Sprintf("build: %s", truncate(spec.Prompt, 72))
			sha, filesChanged, err := b.gitOps.CommitAndPush(ctx, workDir, commitMsg, spec.AutoPush)
			if err != nil {
				b.logger.Warn("git commit/push failed",
					"task_id", task.ID,
					"error", err,
				)
				result.Success = false
				result.Error = fmt.Sprintf("build succeeded but git operations failed: %v", err)
			} else {
				result.CommitSHA = sha
				result.FilesChanged = filesChanged
			}
		}
	}

	return result
}

// parsedBuildSpec holds typed fields extracted from the task spec map.
type parsedBuildSpec struct {
	Prompt     string
	AutoCommit bool
	AutoPush   bool
}

// 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)

	return &parsedBuildSpec{
		Prompt:     prompt,
		AutoCommit: autoCommit,
		AutoPush:   autoPush,
	}, nil
}

// 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] + "..."
}