package bookmarks

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

// dataFile resolves ${XDG_DATA_HOME:-~/.local/share}/lectio/<name> -- the same
// data-dir rule as the sigla store and the bookmarks file.
func dataFile(name string) string {
	base := os.Getenv("XDG_DATA_HOME")
	if base == "" {
		home, err := os.UserHomeDir()
		if err != nil {
			home = "."
		}
		base = filepath.Join(home, ".local", "share")
	}
	return filepath.Join(base, "lectio", name)
}

// Place is the reader's last position, so the TUI reader can reopen where it
// left off (book + chapter + the top-visible verse).
type Place struct {
	Book    string `json:"book"` // canonical English name (Bible-corpus key)
	Chapter int    `json:"chapter"`
	Verse   int    `json:"verse"`
}

// SavePlace persists the reader's last position (atomic temp+rename).
func SavePlace(p Place) error {
	path := dataFile("reader-place.json")
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	data, err := json.MarshalIndent(p, "", "  ")
	if err != nil {
		return err
	}
	tmp := path + ".tmp"
	if err := os.WriteFile(tmp, data, 0o644); err != nil {
		return err
	}
	return os.Rename(tmp, path)
}

// LoadPlace reads the reader's last position; ok is false when none is saved
// (or the file names no book).
func LoadPlace() (Place, bool, error) {
	data, err := os.ReadFile(dataFile("reader-place.json"))
	if err != nil {
		if os.IsNotExist(err) {
			return Place{}, false, nil
		}
		return Place{}, false, err
	}
	var p Place
	if err := json.Unmarshal(data, &p); err != nil {
		return Place{}, false, err
	}
	if p.Book == "" {
		return Place{}, false, nil
	}
	return p, true, nil
}