// hybrid.go implements the Store interface using PocketBase for structured data
// and MinIO for binary chapter/audio blobs.
package storage

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/libnovel/scraper/internal/scraper"
)

// HybridStore satisfies Store by routing structured data to PocketBase and
// binary objects (chapters, audio) to MinIO.
type HybridStore struct {
	pb    *PocketBaseStore
	minio *MinioClient
	log   *slog.Logger
}

// NewHybridStore constructs a HybridStore. It connects to both backends and
// calls EnsureCollections to bootstrap any missing PocketBase collections.
func NewHybridStore(ctx context.Context, pbCfg PocketBaseConfig, minioCfg MinioConfig, log *slog.Logger) (*HybridStore, error) {
	mc, err := NewMinioClient(ctx, minioCfg)
	if err != nil {
		return nil, fmt.Errorf("storage: minio: %w", err)
	}
	pb := NewPocketBaseStore(pbCfg, log)
	// Verify PocketBase credentials before proceeding.
	if err := pb.Ping(ctx); err != nil {
		return nil, fmt.Errorf("storage: pocketbase auth: %w", err)
	}
	if err := pb.EnsureCollections(ctx); err != nil {
		// Non-fatal: 400/422 means collections already exist.
		log.Warn("EnsureCollections returned an error (may be safe to ignore)", "err", err)
	}
	if err := pb.EnsureMigrations(ctx); err != nil {
		log.Warn("EnsureMigrations returned an error", "err", err)
	}
	return &HybridStore{pb: pb, minio: mc, log: log}, nil
}

// ─── Book metadata ────────────────────────────────────────────────────────────

func (h *HybridStore) WriteMetadata(ctx context.Context, meta scraper.BookMeta) error {
	return h.pb.UpsertBook(ctx,
		meta.Slug, meta.Title, meta.Author, meta.Cover,
		meta.Status, meta.Summary, meta.SourceURL,
		meta.Genres, meta.TotalChapters, meta.Ranking,
	)
}

func (h *HybridStore) ReadMetadata(ctx context.Context, slug string) (scraper.BookMeta, bool, error) {
	rec, found, err := h.pb.GetBook(ctx, slug)
	if err != nil || !found {
		return scraper.BookMeta{}, found, err
	}
	return recToBookMeta(rec), true, nil
}

func (h *HybridStore) ListBooks(ctx context.Context) ([]scraper.BookMeta, error) {
	rows, err := h.pb.ListBooks(ctx)
	if err != nil {
		return nil, err
	}
	books := make([]scraper.BookMeta, 0, len(rows))
	for _, r := range rows {
		books = append(books, recToBookMeta(r))
	}
	return books, nil
}

func (h *HybridStore) LocalSlugs(ctx context.Context) (map[string]bool, error) {
	books, err := h.ListBooks(ctx)
	if err != nil {
		return nil, err
	}
	slugs := make(map[string]bool, len(books))
	for _, b := range books {
		slugs[b.Slug] = true
	}
	return slugs, nil
}

func (h *HybridStore) MetadataMtime(ctx context.Context, slug string) int64 {
	t, err := h.pb.BookMetaUpdated(ctx, slug)
	if err != nil {
		h.log.Warn("MetadataMtime: BookMetaUpdated failed", "slug", slug, "err", err)
		return 0
	}
	if t.IsZero() {
		return 0
	}
	return t.Unix()
}

// ─── Chapters ─────────────────────────────────────────────────────────────────

func (h *HybridStore) ChapterExists(ctx context.Context, slug string, ref scraper.ChapterRef) bool {
	return h.minio.ChapterExists(ctx, slug, ref.Volume, ref.Number)
}

func (h *HybridStore) WriteChapter(ctx context.Context, slug string, chapter scraper.Chapter) error {
	content := "# " + chapter.Ref.Title + "\n\n" + chapter.Text + "\n"
	if err := h.minio.PutChapter(ctx, slug, chapter.Ref.Volume, chapter.Ref.Number, content); err != nil {
		return err
	}
	// Update chapter index in PocketBase.
	title, dateLabel := splitChapterTitle(chapter.Ref.Title)
	if err := h.pb.UpsertChapterIdx(ctx, slug, chapter.Ref.Number, title, dateLabel); err != nil {
		h.log.Warn("WriteChapter: failed to upsert chapter index in PocketBase",
			"slug", slug, "chapter", chapter.Ref.Number, "err", err)
	}
	return nil
}

func (h *HybridStore) ReadChapter(ctx context.Context, slug string, n int) (string, error) {
	return h.minio.GetChapter(ctx, slug, 0, n)
}

func (h *HybridStore) ListChapters(ctx context.Context, slug string) ([]ChapterInfo, error) {
	rows, err := h.pb.ListChapterIdx(ctx, slug)
	if err != nil {
		return nil, err
	}
	infos := make([]ChapterInfo, 0, len(rows))
	for _, r := range rows {
		n := int(floatVal(r, "number"))
		title, _ := r["title"].(string)
		date, _ := r["date_label"].(string)
		infos = append(infos, ChapterInfo{Number: n, Title: title, Date: date})
	}
	sort.Slice(infos, func(i, j int) bool { return infos[i].Number < infos[j].Number })
	return infos, nil
}

func (h *HybridStore) CountChapters(ctx context.Context, slug string) int {
	return h.pb.CountChapterIdx(ctx, slug)
}

// ReindexChapters walks all MinIO objects for slug, reads the title from the
// first line of each chapter markdown, and upserts them into chapters_idx.
// This repairs the PocketBase index when it falls out of sync with MinIO.
// Returns the number of chapters indexed and any non-fatal errors encountered.
func (h *HybridStore) ReindexChapters(ctx context.Context, slug string) (int, error) {
	keys, err := h.minio.ListChapterKeys(ctx, slug)
	if err != nil {
		return 0, fmt.Errorf("reindex: list chapter keys: %w", err)
	}

	count := 0
	var errs []string
	for _, key := range keys {
		// Parse chapter number from key: {slug}/vol-N/lo-hi/chapter-N.md
		n := chapterNumberFromKey(key)
		if n <= 0 {
			h.log.Warn("ReindexChapters: could not parse chapter number from key", "key", key)
			continue
		}

		raw, readErr := h.minio.GetChapter(ctx, slug, 0, n)
		if readErr != nil {
			errs = append(errs, fmt.Sprintf("ch%d: %v", n, readErr))
			continue
		}

		// Extract title from first line ("# Title text") or fall back to empty.
		rawTitle := ""
		if line, _, found := strings.Cut(raw, "\n"); found || raw != "" {
			rawTitle = strings.TrimPrefix(strings.TrimSpace(line), "# ")
		}
		title, dateLabel := splitChapterTitle(rawTitle)

		if upsertErr := h.pb.UpsertChapterIdx(ctx, slug, n, title, dateLabel); upsertErr != nil {
			errs = append(errs, fmt.Sprintf("ch%d upsert: %v", n, upsertErr))
			continue
		}
		count++
	}

	if len(errs) > 0 {
		return count, fmt.Errorf("reindex: %d error(s): %s", len(errs), strings.Join(errs, "; "))
	}
	return count, nil
}

// chapterNumberFromKey parses the chapter number from a MinIO object key of the
// form "{slug}/vol-N/lo-hi/chapter-N.md".
func chapterNumberFromKey(key string) int {
	// Grab the filename portion after the last '/'.
	parts := strings.Split(key, "/")
	if len(parts) == 0 {
		return 0
	}
	filename := parts[len(parts)-1]
	// filename is "chapter-N.md"
	filename = strings.TrimSuffix(filename, ".md")
	filename = strings.TrimPrefix(filename, "chapter-")
	n, err := strconv.Atoi(filename)
	if err != nil || n <= 0 {
		return 0
	}
	return n
}

// ─── Ranking ─────────────────────────────────────────────────────────────────

func (h *HybridStore) WriteRankingItem(ctx context.Context, item RankingItem) error {
	return h.pb.UpsertRankingItem(ctx, item)
}

func (h *HybridStore) ReadRankingItems(ctx context.Context) ([]RankingItem, error) {
	return h.pb.ListRankingItems(ctx)
}

func (h *HybridStore) RankingFreshEnough(ctx context.Context, maxAge time.Duration) (bool, error) {
	last, err := h.pb.RankingLastUpdated(ctx)
	if err != nil {
		return false, err
	}
	if last.IsZero() {
		return false, nil
	}
	return time.Since(last) < maxAge, nil
}

// ─── Audio cache ──────────────────────────────────────────────────────────────

func (h *HybridStore) GetAudioCache(ctx context.Context, cacheKey string) (string, bool) {
	filename, ok, err := h.pb.GetAudioCache(ctx, cacheKey)
	if err != nil {
		h.log.Warn("GetAudioCache: PocketBase lookup failed", "cache_key", cacheKey, "err", err)
	}
	return filename, ok
}

func (h *HybridStore) SetAudioCache(ctx context.Context, cacheKey, filename string) error {
	return h.pb.SetAudioCache(ctx, cacheKey, filename)
}

// ─── Reading progress ─────────────────────────────────────────────────────────

func (h *HybridStore) GetProgress(ctx context.Context, sessionID, slug string) (ReadingProgress, bool) {
	ch, updated, ok, err := h.pb.GetProgress(ctx, sessionID, slug)
	if err != nil {
		h.log.Warn("GetProgress: PocketBase lookup failed", "slug", slug, "err", err)
		return ReadingProgress{}, false
	}
	if !ok {
		return ReadingProgress{}, false
	}
	return ReadingProgress{Slug: slug, Chapter: ch, UpdatedAt: updated}, true
}

func (h *HybridStore) SetProgress(ctx context.Context, sessionID string, p ReadingProgress) error {
	return h.pb.SetProgress(ctx, sessionID, p.Slug, p.Chapter)
}

func (h *HybridStore) AllProgress(ctx context.Context, sessionID string) ([]ReadingProgress, error) {
	rows, err := h.pb.AllProgress(ctx, sessionID)
	if err != nil {
		return nil, err
	}
	out := make([]ReadingProgress, 0, len(rows))
	for _, r := range rows {
		slug, _ := r["slug"].(string)
		ch := int(floatVal(r, "chapter"))
		var updated time.Time
		if ts, ok := r["updated"].(string); ok {
			updated, _ = time.Parse(time.RFC3339, ts)
		}
		out = append(out, ReadingProgress{Slug: slug, Chapter: ch, UpdatedAt: updated})
	}
	return out, nil
}

func (h *HybridStore) DeleteProgress(ctx context.Context, sessionID, slug string) error {
	return h.pb.DeleteProgress(ctx, sessionID, slug)
}

// ─── AudioObjectKey ───────────────────────────────────────────────────────────

func (h *HybridStore) AudioObjectKey(slug string, n int, voice string) string {
	return AudioObjectKey(slug, n, voice)
}

func (h *HybridStore) AudioExists(ctx context.Context, key string) bool {
	return h.minio.AudioExists(ctx, key)
}

// ─── PutAudio ─────────────────────────────────────────────────────────────────

func (h *HybridStore) PutAudio(ctx context.Context, key string, data []byte) error {
	return h.minio.PutAudio(ctx, key, data)
}

// ─── Presigned URLs ───────────────────────────────────────────────────────────

func (h *HybridStore) PresignChapter(ctx context.Context, slug string, n int, expires time.Duration) (string, error) {
	return h.minio.PresignChapter(ctx, slug, 0, n, expires)
}

func (h *HybridStore) PresignAudio(ctx context.Context, key string, expires time.Duration) (string, error) {
	return h.minio.PresignAudio(ctx, key, expires)
}

// ─── Browse page snapshots ────────────────────────────────────────────────────

func (h *HybridStore) SaveBrowsePage(ctx context.Context, key, html string) error {
	return h.minio.PutBrowsePage(ctx, key, html)
}

func (h *HybridStore) GetBrowsePage(ctx context.Context, key string) (string, bool, error) {
	return h.minio.GetBrowsePage(ctx, key)
}

func (h *HybridStore) BrowseHTMLKey(domain string, page int) string {
	return BrowseHTMLKey(domain, page)
}

func (h *HybridStore) BrowseCoverKey(domain, slug string) string {
	return BrowseCoverKey(domain, slug)
}

func (h *HybridStore) SaveBrowseAsset(ctx context.Context, key string, data []byte, contentType string) error {
	return h.minio.PutBrowseAsset(ctx, key, data, contentType)
}

func (h *HybridStore) GetBrowseAsset(ctx context.Context, key string) ([]byte, string, bool, error) {
	return h.minio.GetBrowseAsset(ctx, key)
}

// ─── Scraping tasks ───────────────────────────────────────────────────────────

func (h *HybridStore) CreateScrapeTask(ctx context.Context, kind, targetURL string) (string, error) {
	return h.pb.CreateScrapingTask(ctx, kind, targetURL)
}

func (h *HybridStore) UpdateScrapeTask(ctx context.Context, id string, u ScrapeTaskUpdate) error {
	data := map[string]interface{}{
		"status":           u.Status,
		"books_found":      u.BooksFound,
		"chapters_scraped": u.ChaptersScraped,
		"chapters_skipped": u.ChaptersSkipped,
		"errors":           u.Errors,
		"error_message":    u.ErrorMessage,
	}
	if !u.Finished.IsZero() {
		data["finished"] = u.Finished.UTC().Format(time.RFC3339)
	}
	return h.pb.UpdateScrapingTask(ctx, id, data)
}

func (h *HybridStore) ListScrapeTasks(ctx context.Context) ([]ScrapeTask, error) {
	rows, err := h.pb.ListScrapingTasks(ctx)
	if err != nil {
		return nil, err
	}
	tasks := make([]ScrapeTask, 0, len(rows))
	for _, r := range rows {
		t := ScrapeTask{
			ID:              strVal(r, "id"),
			Kind:            strVal(r, "kind"),
			TargetURL:       strVal(r, "target_url"),
			Status:          strVal(r, "status"),
			BooksFound:      int(floatVal(r, "books_found")),
			ChaptersScraped: int(floatVal(r, "chapters_scraped")),
			ChaptersSkipped: int(floatVal(r, "chapters_skipped")),
			Errors:          int(floatVal(r, "errors")),
			ErrorMessage:    strVal(r, "error_message"),
		}
		if ts, ok := r["started"].(string); ok {
			t.Started, _ = time.Parse(time.RFC3339, ts)
		}
		if ts, ok := r["finished"].(string); ok && ts != "" {
			t.Finished, _ = time.Parse(time.RFC3339, ts)
		}
		tasks = append(tasks, t)
	}
	return tasks, nil
}

// ─── helpers ──────────────────────────────────────────────────────────────────

func recToBookMeta(rec map[string]interface{}) scraper.BookMeta {
	m := scraper.BookMeta{
		Slug:      strVal(rec, "slug"),
		Title:     strVal(rec, "title"),
		Author:    strVal(rec, "author"),
		Cover:     strVal(rec, "cover"),
		Status:    strVal(rec, "status"),
		Summary:   strVal(rec, "summary"),
		SourceURL: strVal(rec, "source_url"),
	}
	if tc := floatVal(rec, "total_chapters"); tc > 0 {
		m.TotalChapters = int(tc)
	}
	if rk := floatVal(rec, "ranking"); rk > 0 {
		m.Ranking = int(rk)
	}
	// Genres stored as JSON string or array.
	switch v := rec["genres"].(type) {
	case string:
		_ = json.Unmarshal([]byte(v), &m.Genres)
	case []interface{}:
		for _, g := range v {
			if s, ok := g.(string); ok {
				m.Genres = append(m.Genres, s)
			}
		}
	}
	return m
}

func strVal(m map[string]interface{}, key string) string {
	if v, ok := m[key].(string); ok {
		return v
	}
	return ""
}

// splitChapterTitle mirrors writer.SplitChapterTitle logic (simplified).
func splitChapterTitle(raw string) (title, date string) {
	raw = strings.TrimSpace(raw)
	// Strip leading numeric index.
	if idx := strings.IndexFunc(raw, func(r rune) bool { return r == ' ' || r == '\t' }); idx > 0 {
		prefix := raw[:idx]
		allDigit := true
		for _, c := range prefix {
			if c < '0' || c > '9' {
				allDigit = false
				break
			}
		}
		if allDigit {
			raw = strings.TrimSpace(raw[idx:])
		}
	}
	// Detect trailing relative date.  Build a flat list of all suffixes once
	// to avoid a double-nested loop.
	units := []string{"second", "minute", "hour", "day", "week", "month", "year"}
	suffixes := make([]string, 0, len(units)*2)
	for _, u := range units {
		suffixes = append(suffixes, u+"s ago", u+" ago")
	}
	lower := strings.ToLower(raw)
	for _, suffix := range suffixes {
		idx := strings.LastIndex(lower, suffix)
		if idx <= 0 {
			continue
		}
		// Find start of the numeric token that precedes the unit.
		// Strip any whitespace that separates the number from the unit so
		// that LastIndex finds the space before the digit, not the one
		// between the digit and the unit word.
		before := strings.TrimRight(raw[:idx], " \t")
		start := strings.LastIndex(before, " ")
		if start < 0 {
			start = 0
		} else {
			start++ // advance past the space to point at the digit
		}
		numPart := strings.TrimSpace(raw[start:idx])
		fields := strings.Fields(numPart)
		if len(fields) > 0 {
			if _, err := strconv.Atoi(fields[0]); err == nil {
				return strings.TrimSpace(raw[:start]), strings.TrimSpace(raw[start : idx+len(suffix)])
			}
		}
	}
	return raw, ""
}