/* SPDX-License-Identifier: GPL-2.0 */

#include <osl.h>
#include <lopsub.h>

#include "para.h"
#include "error.h"
#include "string.h"
#include "afh.h"
#include "afs.h"
#include "ipc.h"

/** \file playlist.c Functions for loading and saving playlists. */

/**
 * The state of a playlist instance.
 *
 * A structure of this type is allocated and initialized at playlist load time.
 */
struct selector_instance {
	/** The name of the playlist. */
	char *name;
	/** The number of entries currently in the playlist. */
	unsigned length;
	/** Contains all valid paths of the playlist. */
	struct osl_table *score_table;
};

static int add_playlist_entry(char *path, void *data)
{
	struct selector_instance *si = data;
	struct osl_row *aft_row;
	int ret = aft_get_row_of_path(path, &aft_row);

	if (ret < 0) {
		PARA_NOTICE_LOG("%s: %s\n", path, para_strerror(-ret));
		return 1;
	}
	ret = score_add(aft_row, -si->length, si->score_table);
	if (ret < 0) {
		PARA_ERROR_LOG("failed to add %s: %s\n", path, para_strerror(-ret));
		return ret;
	}
	si->length++;
	return 1;
}

static int check_playlist_path(char *path, void *data)
{
	struct afs_callback_arg *aca = data;
	struct osl_row *aft_row;
	int ret = aft_get_row_of_path(path, &aft_row);

	if (ret < 0)
		para_printf(&aca->pbout, "%s: %s\n", path, para_strerror(-ret));
	return 1; /* do not fail the loop on bad paths */
}

static int check_playlist(struct osl_row *row, void *data)
{
	struct afs_callback_arg *aca = data;
	struct para_buffer *pb = &aca->pbout;
	struct osl_object playlist_def;
	char *playlist_name;
	int ret = pl_get_name_and_def_by_row(row, &playlist_name, &playlist_def);

	if (ret < 0) {
		if (ret == osl(-E_OSL_EMPTY)) {
			para_printf(&aca->pbout,
				"not checking empty playlist %s\n",
				playlist_name);
			return 0;
		}
		para_printf(pb, "failed to get playlist data: %s\n",
			para_strerror(-ret));
		return ret;
	}
	if (*playlist_name) { /* skip dummy row */
		para_printf(pb, "checking playlist %s...\n", playlist_name);
		for_each_line(FELF_READ_ONLY, playlist_def.data,
			playlist_def.size, check_playlist_path, aca);
	}
	osl_close_disk_object(&playlist_def);
	return 1;
}

/* Invalid paths are reported, but are not considered an error. */
static int playlist_check(struct afs_callback_arg *aca)
{
	para_printf(&aca->pbout, "checking playlists...\n");
	return osl(osl_rbtree_loop(playlists_table, BLOBCOL_ID, aca,
		check_playlist));
}

static void playlist_unload(struct selector_instance *si)
{
	score_close(si->score_table);
	free(si->name);
	free(si);
}

/*
 * Populate the score table from the paths of a playlist database object.
 *
 * This loads the blob object which corresponds to the given name from the
 * playlist table. Each line of the blob is regarded as a path to be looked
 * up in the audio file table. If the path lookup succeeds, a reference to
 * the corresponding row of the audio file table is added to the score table.
 *
 * Returns the length of the loaded playlist on success, negative error code
 * else. Files which are listed in the playlist, but are not contained in
 * the database are ignored. This is not considered an error.
 */
static int playlist_load(const char *name, struct para_buffer *pbout,
		struct afs_callback_arg *aca, struct selector_instance **result)
{
	int ret;
	struct selector_instance *si;
	struct osl_object playlist_def;

	*result = NULL;
	if (!name || !*name) {
		afs_error(aca, "empty playlist name\n");
		return -ERRNO_TO_PARA_ERROR(EINVAL);
	}
	ret = pl_get_def_by_name(name, &playlist_def);
	if (ret < 0)
		goto err;
	si = zalloc(sizeof(*si));
	score_open(&si->score_table);
	ret = for_each_line(FELF_READ_ONLY, playlist_def.data,
		playlist_def.size, add_playlist_entry, si);
	osl_close_disk_object(&playlist_def);
	if (ret < 0)
		goto close_score_table;
	ret = -E_PLAYLIST_EMPTY;
	if (si->length == 0)
		goto close_score_table;
	/* success */
	if (pbout)
		para_printf(pbout, "playlist %s: %u files\n", name, si->length);
	si->name = para_strdup(name);
	*result = si;
	return si->length;
close_score_table:
	score_close(si->score_table);
	free(si);
err:
	afs_error(aca, "unable to load playlist %s\n", name);
	return ret;
}

static int playlist_loop(int (*cb)(struct osl_row *aft_row, long score, void *data),
		struct selector_instance *si, void *data)
{
	return score_loop(cb, si->score_table, data);
}

static int search_path(char *path, void *data)
{
	if (strcmp(path, data))
		return 1;
	return -E_PATH_FOUND;
}

static int handle_add_or_rename(struct osl_row *aft_row, struct osl_table *score_table)
{
	int ret;
	struct osl_object playlist_def;
	char *path;

	ret = score_delete(aft_row, score_table);
	if (ret < 0)
		return ret;
	if (ret > 0)
		current_selector_instance->length--;
	ret = get_audio_file_path_of_row(aft_row, &path);
	if (ret < 0)
		return ret;
	ret = pl_get_def_by_name(current_selector_instance->name, &playlist_def);
	if (ret < 0)
		return ret;
	ret = for_each_line(FELF_READ_ONLY, playlist_def.data,
		playlist_def.size, search_path, path);
	osl_close_disk_object(&playlist_def);
	if (ret == -E_PATH_FOUND) { /* path is in playlist */
		ret = score_add(aft_row, 0, NULL); /* play it immediately */
		if (ret >= 0)
			current_selector_instance->length++;
	}
	return ret;
}

/**
 * Handle afs events relevant to playlists.
 *
 * \param event The event type.
 * \param data Depends on the event type.
 *
 * \return Standard.
 */
int playlists_event_handler(enum afs_events event, void *data)
{
	struct osl_table *score_table;

	if (!current_selector_instance || current_selector_id != SEL_PLAYLIST)
		return 1;
	score_table = current_selector_instance->score_table;
	switch (event) {
	case VSS_NEW_AUDIO_FILE:
		return score_move_to_end(data, score_table);
	case AUDIO_FILE_ADD:
	case AUDIO_FILE_RENAME:
		return handle_add_or_rename(data, score_table);
	case AUDIO_FILE_REMOVE: {
		int ret = score_delete(data, score_table);
		if (ret > 0) /* file was in the playlist */
			current_selector_instance->length--;
		return ret;
		}
	default:
		return 1;
	}
}

static int playlist_get_best(struct osl_row **aft_row, long *score,
		struct selector_instance *si)
{
	return score_get_best(aft_row, score, si->score_table);
}

static int playlist_invalidate(struct osl_row *aft_row, struct selector_instance *si)
{
	return score_delete(aft_row, si->score_table);
}

/**
 * Functions for playlist handling.
 *
 * The playlist selector reads a playlist stored in the playlist blob table
 * and considers an audio file amissible if it is listed there.
 *
 * \sa \ref playlist_selector_operations.
 */
const struct selector_operations playlist_selector_operations = {
	.load = playlist_load,
	.loop = playlist_loop,
	.unload = playlist_unload,
	.check = playlist_check,
	.get_best = playlist_get_best,
	.invalidate = playlist_invalidate,
};