package ticket

import (
	"fmt"
	"os"
	"os/exec"
	"strings"
)

// FormatEditDocument is the markdown representation used for external editing.
// Format:
//
//	# Title
//
//	optional description body…
func FormatEditDocument(t Ticket) string {
	title := strings.TrimSpace(t.Title)
	title = strings.TrimLeft(title, "#")
	title = strings.TrimSpace(title)

	var b strings.Builder
	b.WriteString("# ")
	b.WriteString(title)
	b.WriteString("\n")
	if desc := strings.TrimSpace(t.Description); desc != "" {
		b.WriteString("\n")
		b.WriteString(desc)
		if !strings.HasSuffix(desc, "\n") {
			b.WriteString("\n")
		}
	}
	return b.String()
}

// ParseEditDocument extracts title and description from an edited markdown file.
func ParseEditDocument(content string) (title, description string, err error) {
	content = strings.ReplaceAll(content, "\r\n", "\n")
	content = strings.TrimSpace(content)
	if content == "" {
		return "", "", fmt.Errorf("ticket content is empty")
	}

	lines := strings.Split(content, "\n")
	first := strings.TrimSpace(lines[0])
	if strings.HasPrefix(first, "#") {
		title = strings.TrimSpace(strings.TrimLeft(first, "#"))
		rest := strings.Join(lines[1:], "\n")
		description = strings.TrimSpace(rest)
	} else {
		title = first
		rest := strings.Join(lines[1:], "\n")
		description = strings.TrimSpace(rest)
	}
	if title == "" {
		return "", "", fmt.Errorf("ticket title is required")
	}
	return title, description, nil
}

// WriteEditFile writes the ticket to a temp .md file and returns its path.
func WriteEditFile(t Ticket) (string, error) {
	f, err := os.CreateTemp("", "task-master-ticket-*.md")
	if err != nil {
		return "", fmt.Errorf("create temp file: %w", err)
	}
	path := f.Name()
	if _, err := f.WriteString(FormatEditDocument(t)); err != nil {
		_ = f.Close()
		_ = os.Remove(path)
		return "", fmt.Errorf("write temp file: %w", err)
	}
	if err := f.Close(); err != nil {
		_ = os.Remove(path)
		return "", fmt.Errorf("close temp file: %w", err)
	}
	return path, nil
}

// ResolveEditor returns the user's preferred editor command string.
// Order: $EDITOR → $VISUAL → nvim → vim → vi.
func ResolveEditor() string {
	if ed := strings.TrimSpace(os.Getenv("EDITOR")); ed != "" {
		return ed
	}
	if ed := strings.TrimSpace(os.Getenv("VISUAL")); ed != "" {
		return ed
	}
	for _, cand := range []string{"nvim", "vim", "vi"} {
		if _, err := exec.LookPath(cand); err == nil {
			return cand
		}
	}
	return "vi"
}

// EditorCmd builds a command that opens path in the default terminal editor.
// Supports multi-word EDITOR values like "code --wait".
func EditorCmd(path string) *exec.Cmd {
	ed := ResolveEditor()
	cmd := exec.Command("sh", "-c", ed+` "$1"`, "--", path)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd
}