// 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"
	"fmt"
	"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"`
	Verse   int      `json:"verse,omitempty"` // 0 = whole chapter; >0 = a specific verse
	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.tsv -- a plain, universal TSV like the sigla store) and returns a
// ready Store. It never fails: a missing file simply reads as an empty list.
// A one-time migration converts a pre-existing bookmarks.json to TSV.
func Open() *Store {
	s := &Store{path: dataFile("bookmarks.tsv")}
	s.migrate()
	return s
}

// migrate converts an old bookmarks.json to the TSV store once (backing the
// JSON up as bookmarks.json.migrated), if no TSV file exists yet.
func (s *Store) migrate() {
	if _, err := os.Stat(s.path); err == nil {
		return // TSV already present
	}
	jsonPath := dataFile("bookmarks.json")
	data, err := os.ReadFile(jsonPath)
	if err != nil {
		return // no legacy JSON
	}
	var list []Bookmark
	if len(data) > 0 {
		if err := json.Unmarshal(data, &list); err != nil {
			return
		}
	}
	if s.save(list) == nil {
		_ = os.Rename(jsonPath, jsonPath+".migrated")
	}
}

// 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
}

// bookmarksHeader is the TSV column header (also skipped when reading).
const bookmarksHeader = "id\tbook\tchapter\tverse\ttags\tcreated\tnote"

// tsvClean strips tab/newline characters so free text stays in one TSV field.
func tsvClean(s string) string {
	r := strings.NewReplacer("\t", " ", "\n", " ", "\r", " ")
	return r.Replace(s)
}

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
	for _, line := range strings.Split(string(data), "\n") {
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		f := strings.Split(line, "\t")
		if len(f) < 7 || f[0] == "id" { // skip the header row / malformed lines
			continue
		}
		chap, _ := strconv.Atoi(f[2])
		verse, _ := strconv.Atoi(f[3])
		list = append(list, Bookmark{
			ID: f[0], Book: f[1], Chapter: chap, Verse: verse,
			Tags: ParseTags(f[4]), Created: f[5], Note: f[6],
		})
	}
	return list, nil
}

// save writes the store as TSV with a header row (note is the last column, so
// stray content never shifts the columns; tabs/newlines are sanitized).
func (s *Store) save(list []Bookmark) error {
	if err := os.MkdirAll(filepath.Dir(s.path), 0o755); err != nil {
		return err
	}
	var b strings.Builder
	b.WriteString(bookmarksHeader + "\n")
	for _, bm := range list {
		fmt.Fprintf(&b, "%s\t%s\t%d\t%d\t%s\t%s\t%s\n",
			bm.ID, tsvClean(bm.Book), bm.Chapter, bm.Verse,
			tsvClean(strings.Join(bm.Tags, ",")), bm.Created, tsvClean(bm.Note))
	}
	tmp := s.path + ".tmp"
	if err := os.WriteFile(tmp, []byte(b.String()), 0o644); err != nil {
		return err
	}
	return os.Rename(tmp, s.path)
}