// Package bookmarks is lectio's small persistent store of reader bookmarks
// (a book+chapter with a note and tags), a JSON file in the data dir so the
// web reader -- and, later, the TUI/CLI -- can share it.
package bookmarks

import (
	"encoding/json"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"
)

// Bookmark is one saved place in the Bible: a book+chapter with a note and tags.
type Bookmark struct {
	ID      string   `json:"id"`
	Book    string   `json:"book"` // canonical English name (Bible-corpus key)
	Chapter int      `json:"chapter"`
	Note    string   `json:"note"`
	Tags    []string `json:"tags"`
	Created string   `json:"created"` // RFC3339
}

// Store is the bookmarks file, guarded by a mutex (each op load-modify-saves).
type Store struct {
	path string
	mu   sync.Mutex
}

// Open resolves the store path (${XDG_DATA_HOME:-~/.local/share}/lectio/
// bookmarks.json, mirroring the sigla store) and returns a ready Store. It never
// fails: a missing file simply reads as an empty list.
func Open() *Store {
	base := os.Getenv("XDG_DATA_HOME")
	if base == "" {
		home, err := os.UserHomeDir()
		if err != nil {
			home = "."
		}
		base = filepath.Join(home, ".local", "share")
	}
	return &Store{path: filepath.Join(base, "lectio", "bookmarks.json")}
}

// ParseTags splits a comma-separated tag string into trimmed, non-empty tags.
func ParseTags(s string) []string {
	var out []string
	for _, t := range strings.Split(s, ",") {
		if t = strings.TrimSpace(t); t != "" {
			out = append(out, t)
		}
	}
	return out
}

// List returns all bookmarks, newest first. A missing file is an empty list,
// not an error. If tag is non-empty, only bookmarks carrying that tag are returned.
func (s *Store) List(tag string) ([]Bookmark, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	all, err := s.load()
	if err != nil {
		return nil, err
	}
	sort.SliceStable(all, func(i, j int) bool { return all[i].Created > all[j].Created })
	if tag == "" {
		return all, nil
	}
	var out []Bookmark
	for _, b := range all {
		for _, t := range b.Tags {
			if t == tag {
				out = append(out, b)
				break
			}
		}
	}
	return out, nil
}

// Add assigns an ID + Created timestamp, appends the bookmark, and saves.
func (s *Store) Add(b Bookmark) (Bookmark, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	all, err := s.load()
	if err != nil {
		return Bookmark{}, err
	}
	b.ID = strconv.FormatInt(time.Now().UnixNano(), 36)
	// RFC3339Nano (not plain RFC3339): two Adds can land in the same
	// wall-clock second, and List's newest-first sort needs the extra
	// precision to break the tie correctly (RFC3339Nano is still valid
	// RFC3339 -- fractional seconds are permitted, just usually omitted).
	b.Created = time.Now().Format(time.RFC3339Nano)
	all = append(all, b)
	if err := s.save(all); err != nil {
		return Bookmark{}, err
	}
	return b, nil
}

// Delete removes the bookmark with id (a no-op if absent).
func (s *Store) Delete(id string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	all, err := s.load()
	if err != nil {
		return err
	}
	kept := all[:0]
	for _, b := range all {
		if b.ID != id {
			kept = append(kept, b)
		}
	}
	return s.save(kept)
}

// Tags returns the sorted, de-duplicated set of all tags in use.
func (s *Store) Tags() ([]string, error) {
	all, err := s.List("")
	if err != nil {
		return nil, err
	}
	set := map[string]bool{}
	for _, b := range all {
		for _, t := range b.Tags {
			set[t] = true
		}
	}
	tags := make([]string, 0, len(set))
	for t := range set {
		tags = append(tags, t)
	}
	sort.Strings(tags)
	return tags, nil
}

func (s *Store) load() ([]Bookmark, error) {
	data, err := os.ReadFile(s.path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}
	var list []Bookmark
	if len(data) == 0 {
		return nil, nil
	}
	if err := json.Unmarshal(data, &list); err != nil {
		return nil, err
	}
	return list, nil
}

func (s *Store) save(list []Bookmark) error {
	if err := os.MkdirAll(filepath.Dir(s.path), 0o755); err != nil {
		return err
	}
	data, err := json.MarshalIndent(list, "", "  ")
	if err != nil {
		return err
	}
	tmp := s.path + ".tmp"
	if err := os.WriteFile(tmp, data, 0o644); err != nil {
		return err
	}
	return os.Rename(tmp, s.path)
}