package workon

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"

	"gmgauthier.com/grokkit/config"
	"gmgauthier.com/grokkit/internal/grok"
	"gmgauthier.com/grokkit/internal/logger"
	"gmgauthier.com/grokkit/internal/todo"
)

// Run executes the full transactional workon flow per todo/doing/workon.md spec.
func Run(title, customMsg string, isFix, isComplete bool) error {
	if title == "" {
		return fmt.Errorf("todo_item_title is required")
	}

	logger.Info("workon starting", "title", title, "fix", isFix, "complete", isComplete)

	// 1. Bootstrap todo structure if missing
	if err := todo.Bootstrap(); err != nil {
		return fmt.Errorf("todo bootstrap failed: %w", err)
	}

	if isComplete {
		return completeItem(title, isFix)
	}

	// 2. Handle todo or fix mode
	branchName := title
	mdPath := filepath.Join("todo", "doing", title+".md")

	if isFix {
		if err := createFixFile(mdPath, title); err != nil {
			return fmt.Errorf("create fix file failed: %w", err)
		}
	} else {
		if err := moveQueuedToDoing(title); err != nil {
			return fmt.Errorf("move to doing failed: %w", err)
		}
	}

	// 3. Create git branch (safe)
	if err := createGitBranch(branchName); err != nil {
		return fmt.Errorf("failed to create branch %s: %w", branchName, err)
	}

	// 4. Generate + append Work Plan via Grok
	if err := appendWorkPlan(mdPath, title); err != nil {
		return fmt.Errorf("failed to generate/append Work Plan: %w", err)
	}

	// 5. Commit
	commitMsg := customMsg
	if commitMsg == "" {
		commitMsg = fmt.Sprintf("Start working on %s", title)
	}
	if err := commitChanges(commitMsg); err != nil {
		return fmt.Errorf("commit failed: %w", err)
	}

	// 6. Optional post-steps (graceful)
	runCnaddIfAvailable(title)
	openIDEIfConfigured()

	logger.Info("workon transaction complete", "branch", branchName, "mode", map[bool]string{true: "fix", false: "todo"}[isFix])
	return nil
}

func moveQueuedToDoing(title string) error {
	src := filepath.Join("todo", "queued", title+".md")
	dst := filepath.Join("todo", "doing", title+".md")
	if err := os.Rename(src, dst); err != nil {
		return fmt.Errorf("move %s -> doing failed: %w", title, err)
	}
	return nil
}

func createFixFile(path, title string) error {
	content := fmt.Sprintf("# %s\n\n## Work Plan\n\n", title)
	return os.WriteFile(path, []byte(content), 0644)
}

func createGitBranch(name string) error {
	// Safe: if branch already exists, just checkout it; else create new
	if err := exec.Command("git", "checkout", name).Run(); err == nil {
		return nil
	}
	return exec.Command("git", "checkout", "-b", name).Run()
}

func appendWorkPlan(path, title string) error {
	content := readFileContent(path)

	prompt := fmt.Sprintf(`You are helping implement a todo item titled "%s".

Here is the current markdown content of the todo/fix file:

%s

Generate a concise, actionable **Work Plan** section.
Use numbered steps. Be specific to this item. Include testing and commit notes where relevant.
Output ONLY the markdown starting with "## Work Plan" — no extra text, no introduction.`, title, content)

	// Real Grok call using the project's standard client (StreamSilent for clean output)
	client := grok.NewClient()
	model := config.GetModel("workon", "grok-4-fast-non-reasoning")
	plan := client.StreamSilent([]map[string]string{
		{"role": "system", "content": "You are a precise software engineering assistant."},
		{"role": "user", "content": prompt},
	}, model) // or pull model from config/env if available

	// Append the plan
	f, err := os.OpenFile(path, os.O_APPEND|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	defer func() {
		if cerr := f.Close(); cerr != nil {
			logger.Error("failed to close todo file", "err", cerr)
		}
	}()
	_, err = f.WriteString(plan)
	return err
}

func readFileContent(path string) string {
	b, _ := os.ReadFile(path)
	return string(b)
}

func commitChanges(msg string) error {
	if err := exec.Command("git", "add", "todo/").Run(); err != nil {
		return err
	}
	return exec.Command("git", "commit", "-m", msg).Run()
}

func completeItem(title string, isFix bool) error {
	src := filepath.Join("todo", "doing", title+".md")
	dst := filepath.Join("todo", "completed", title+".md")
	if err := os.Rename(src, dst); err != nil {
		return fmt.Errorf("move to completed failed: %w", err)
	}

	// TODO: update todo/README.md index under ## Completed (for non-fixes)
	if !isFix {
		logger.Info("TODO: update index README for completed todo")
	}

	commitMsg := fmt.Sprintf("Complete work on %s", title)
	if err := commitChanges(commitMsg); err != nil {
		return fmt.Errorf("complete commit failed: %w", err)
	}
	return nil
}

func runCnaddIfAvailable(title string) {
	if _, err := exec.LookPath("cnadd"); err == nil {
		_ = exec.Command("cnadd", "log", fmt.Sprintf("started work on %s", title)).Run()
	}
}

func openIDEIfConfigured() {
	// TODO: implement via config once internal/config or root config supports IDE command
	// For now, silent graceful fallback per spec
	logger.Debug("IDE open skipped (config support pending)")
}