package media

import (
	"net/http"
	"strconv"

	"github.com/mithral/vellum/internal/auth"
	"github.com/mithral/vellum/internal/httpx"
)

// itemRow is the browse-list shape.
type itemRow struct {
	ID        int64  `json:"id"`
	LibraryID int64  `json:"library_id"`
	Kind      string `json:"kind"`
	Path      string `json:"path"`
	Title     string `json:"title"`
	Year      int    `json:"year"`
}

// handleListItems lists items across every library the caller may read,
// optionally filtered by media kind or a single library.
//
// This is what powers "Browse > Ebooks" — one request, scoped by the same
// access-control chokepoint as everything else.
func (h *Handlers) handleListItems(w http.ResponseWriter, r *http.Request, u auth.User) {
	ctx := r.Context()

	libs, err := auth.VisibleLibraryIDs(ctx, h.db, u)
	if err != nil {
		h.fail(w, "visible libraries", err)
		return
	}

	limit := 300
	if v := r.URL.Query().Get("limit"); v != "" {
		if n, err := strconv.Atoi(v); err == nil && n > 0 && n <= 1000 {
			limit = n
		}
	}

	offset := 0
	if v := r.URL.Query().Get("offset"); v != "" {
		if n, err := strconv.Atoi(v); err == nil && n >= 0 {
			offset = n
		}
	}

	if len(libs) == 0 {
		httpx.WriteJSON(w, http.StatusOK, map[string]any{
			"items":  []itemRow{},
			"total":  0,
			"offset": offset,
			"limit":  limit,
		})
		return
	}

	in, args := inClause(libs)
	where := `missing = 0 AND library_id IN (` + in + `)`

	if kind := r.URL.Query().Get("kind"); kind != "" {
		where += ` AND kind = ?`
		args = append(args, kind)
	}
	if libStr := r.URL.Query().Get("library_id"); libStr != "" {
		libID, err := strconv.ParseInt(libStr, 10, 64)
		if err != nil || libID <= 0 {
			httpx.WriteError(w, http.StatusBadRequest, "invalid library_id")
			return
		}
		where += ` AND library_id = ?`
		args = append(args, libID)
	}

	// total counts every matching row, independent of the page window.
	var total int
	if err := h.db.QueryRowContext(ctx,
		`SELECT COUNT(*) FROM media_items WHERE `+where, args...).Scan(&total); err != nil {
		h.fail(w, "count items", err)
		return
	}

	query := `SELECT id, library_id, kind, path, title, COALESCE(year, 0)
	          FROM media_items
	          WHERE ` + where + ` ORDER BY sort_title LIMIT ? OFFSET ?`
	pageArgs := append(append([]any{}, args...), limit, offset)

	rows, err := h.db.QueryContext(ctx, query, pageArgs...)
	if err != nil {
		h.fail(w, "list items", err)
		return
	}
	defer rows.Close()

	items := []itemRow{}
	for rows.Next() {
		var it itemRow
		if err := rows.Scan(&it.ID, &it.LibraryID, &it.Kind, &it.Path, &it.Title, &it.Year); err != nil {
			h.fail(w, "scan item", err)
			return
		}
		items = append(items, it)
	}
	if err := rows.Err(); err != nil {
		h.fail(w, "iterate items", err)
		return
	}

	httpx.WriteJSON(w, http.StatusOK, map[string]any{
		"items":  items,
		"total":  total,
		"offset": offset,
		"limit":  limit,
	})
}