package claude

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"time"
)

// Loader reads Claude Code state files from a local claude directory (typically ~/.claude).
//
// Keep this minimal for now; more helpers (e.g. ListDir / FileInfo) can be added later.
type Loader struct {
	claudeDir string
}

type DirEntry struct {
	Name  string `json:"name"`
	IsDir bool   `json:"isDir"`
}

type FileMeta struct {
	Path    string `json:"path"`
	Exists  bool   `json:"exists"`
	Size    int64  `json:"size"`
	ModTime string `json:"modTime"`
}

func NewLoader(claudeDir string) *Loader {
	return &Loader{claudeDir: claudeDir}
}

func (l *Loader) ClaudeDir() string { return l.claudeDir }

func (l *Loader) LoadStatsCache() (*StatsCache, error) {
	if l.claudeDir == "" {
		return nil, fmt.Errorf("claude dir is empty")
	}

	p := filepath.Join(l.claudeDir, "stats-cache.json")
	b, err := os.ReadFile(p)
	if err != nil {
		return nil, fmt.Errorf("read stats cache %q: %w", p, err)
	}

	var stats StatsCache
	if err := json.Unmarshal(b, &stats); err != nil {
		return nil, fmt.Errorf("parse stats cache %q: %w", p, err)
	}

	return &stats, nil
}

func (l *Loader) ListDir(name string) ([]DirEntry, error) {
	if l.claudeDir == "" {
		return nil, fmt.Errorf("claude dir is empty")
	}

	entries, err := os.ReadDir(filepath.Join(l.claudeDir, name))
	if err != nil {
		return nil, fmt.Errorf("read dir %q: %w", name, err)
	}

	out := make([]DirEntry, 0, len(entries))
	for _, e := range entries {
		out = append(out, DirEntry{Name: e.Name(), IsDir: e.IsDir()})
	}
	return out, nil
}

func (l *Loader) PathExists(relPath string) bool {
	if l.claudeDir == "" {
		return false
	}
	_, err := os.Stat(filepath.Join(l.claudeDir, relPath))
	return err == nil
}

func (l *Loader) FileMeta(relPath string) (FileMeta, error) {
	if l.claudeDir == "" {
		return FileMeta{}, fmt.Errorf("claude dir is empty")
	}

	p := filepath.Join(l.claudeDir, relPath)
	st, err := os.Stat(p)
	if err != nil {
		if os.IsNotExist(err) {
			return FileMeta{Path: relPath, Exists: false}, nil
		}
		return FileMeta{}, fmt.Errorf("stat %q: %w", p, err)
	}

	return FileMeta{
		Path:    relPath,
		Exists:  true,
		Size:    st.Size(),
		ModTime: st.ModTime().UTC().Format(time.RFC3339),
	}, nil
}