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

/** \file afh_common.c Common audio format handler functions. */

#include <sys/mman.h> /* mmap */
#include <sys/types.h>

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

/** The list of all status items */
const char *status_item_list[] = {STATUS_ITEMS};

/**
 * For each audio file the number of its audio format is stored in the
 * database. Therefore this list, in particular its order, is part of the ABI.
 * So it's only OK to append new audio formats. All audio formats are listed
 * here, regardless of whether the audio format handler is compiled in.
 */
#define ALL_AUDIO_FORMATS \
	AUDIO_FORMAT(mp3) \
	AUDIO_FORMAT(ogg) \
	AUDIO_FORMAT(aac) \
	AUDIO_FORMAT(wma) \
	AUDIO_FORMAT(spx) \
	AUDIO_FORMAT(flac) \
	AUDIO_FORMAT(opus) \

/** \cond doxygen_ignore */
#define AUDIO_FORMAT(_fmt) #_fmt,
static const char * const audio_format_names[] = {ALL_AUDIO_FORMATS};
#undef AUDIO_FORMAT
/* Weak declarations must be public. */
#define AUDIO_FORMAT(_fmt) \
	struct audio_format_handler _fmt ## _afh __attribute__ ((weak)) \
	= {.get_file_info = NULL};
ALL_AUDIO_FORMATS
#undef AUDIO_FORMAT
#define AUDIO_FORMAT(_fmt) & _fmt ## _afh,
static struct audio_format_handler *afl[] = {ALL_AUDIO_FORMATS};
#undef AUDIO_FORMAT
#define NUM_AUDIO_FORMATS (ARRAY_SIZE(afl))
/** \endcond */

/**
 * Get the name of the given audio format.
 *
 * \param i The audio format number.
 *
 * \return This returns a pointer to statically allocated memory so it
 * must not be freed by the caller.
 */
const char *audio_format_name(int i)
{
	if (i < 0 || i >= NUM_AUDIO_FORMATS)
		return "???";
	return audio_format_names[i];
}

/** Iterate over each supported audio format. */
#define FOR_EACH_AUDIO_FORMAT(i) for (i = 0; i < NUM_AUDIO_FORMATS; i++)

/**
 * Tell whether an audio format handler provides chunk tables.
 *
 * Each audio format handler either provides a chunk table or supports dynamic
 * chunks.
 *
 * \param audio_format_id Offset in the afl array.
 *
 * \return True if dynamic chunks are supported, false if the audio format
 * handler provides chunk tables.
 */
bool afh_supports_dynamic_chunks(int audio_format_id)
{
	return afl[audio_format_id]->get_chunk;
}

/**
 * Guess the audio format judging from filename.
 *
 * This looks for matches in the \ref audio_format_handler::suffixes array
 * of each audio format handler. The function has to be implemented in this
 * file because the audio format handler array is a static variable.
 *
 * \param name The filename.
 *
 * \return This function returns -E_AUDIO_FORMAT if it has no idea what kind
 * of audio file this might be. Otherwise the (non-negative) number of the
 * audio format is returned.
 */
int guess_audio_format(const char *name)
{
	int i,j, len = strlen(name);

	FOR_EACH_AUDIO_FORMAT(i) {
		if (!afl[i]->get_file_info)
			continue;
		for (j = 0; afl[i]->suffixes[j]; j++) {
			const char *p = afl[i]->suffixes[j];
			int plen = strlen(p);
			if (len < plen + 1)
				continue;
			if (name[len - plen - 1] != '.')
				continue;
			if (strcasecmp(name + len - plen, p))
				continue;
//			PARA_DEBUG_LOG("might be %s\n", audio_format_name(i));
			return i;
		}
	}
	return -E_AUDIO_FORMAT;
}

static int get_file_info(int format, const char *path, char *data,
		size_t size, struct afh_info *afhi)
{
	int ret;
	const char *fmt = audio_format_name(format);

	memset(afhi, 0, sizeof(*afhi));
	ret = afl[format]->get_file_info(data, size, afhi);
	if (ret < 0) {
		PARA_WARNING_LOG("%s: %s format not detected: %s\n",
			path, fmt, para_strerror(-ret));
		return ret;
	}
	PARA_NOTICE_LOG("%s: detected %s format\n", path, fmt);
	return format;
}

/**
 * Initialize an instance of struct \ref afh_info.
 *
 * \param path The full path of the audio file.
 * \param data Pointer to the contents of the (mapped) file.
 * \param size The file size in bytes.
 * \param afhi Result pointer.
 *
 * This function guesses the audio format from the given pathname and calls
 * \ref audio_format_handler::get_file_info() of the audio format handler
 * that corresponds to this guess. If this doesn't work, all other audio
 * format handlers are tried until one is found that can handle the file or
 * we run out of audio format handlers to try.
 *
 * \return The number of the audio format on success, -E_AUDIO_FORMAT if no
 * compiled in audio format handler is able to handle the file.
 */
int compute_afhi(const char *path, char *data, size_t size,
		struct afh_info *afhi)
{
	int ret, i, format;

	format = guess_audio_format(path);
	if (format >= 0) {
		ret = get_file_info(format, path, data, size, afhi);
		if (ret >= 0)
			goto success;
	}
	FOR_EACH_AUDIO_FORMAT(i) {
		if (!afl[i]->get_file_info)
			continue;
		if (i == format) /* we already tried this one to no avail */
			continue;
		ret = get_file_info(i, path, data, size, afhi);
		if (ret >= 0)
			goto success;
	}
	return -E_AUDIO_FORMAT;
success:
	if (!afhi->techinfo)
		afhi->techinfo = para_strdup(NULL);
	if (!afhi->tags.artist)
		afhi->tags.artist = para_strdup(NULL);
	if (!afhi->tags.title)
		afhi->tags.title = para_strdup(NULL);
	if (!afhi->tags.year)
		afhi->tags.year = para_strdup(NULL);
	if (!afhi->tags.album)
		afhi->tags.album = para_strdup(NULL);
	if (!afhi->tags.comment)
		afhi->tags.comment = para_strdup(NULL);
	PARA_DEBUG_LOG("techinfo: %s\n", afhi->techinfo);
	PARA_DEBUG_LOG("artist: %s\n", afhi->tags.artist);
	PARA_DEBUG_LOG("title: %s\n", afhi->tags.title);
	PARA_DEBUG_LOG("year: %s\n", afhi->tags.year);
	PARA_DEBUG_LOG("album: %s\n", afhi->tags.album);
	PARA_DEBUG_LOG("comment: %s\n", afhi->tags.comment);
	return ret;
}

/**
 * Deallocate the contents of an afh_info structure.
 *
 * \param afhi The structure to clear.
 *
 * This only frees the memory the various pointer fields of the \ref afh_info
 * structure point to. It does *not* attempt to call free(3) on its argument.
 */
void clear_afhi(struct afh_info *afhi)
{
	if (!afhi)
		return;
	free(afhi->chunk_table);
	free(afhi->techinfo);
	free(afhi->tags.artist);
	free(afhi->tags.title);
	free(afhi->tags.year);
	free(afhi->tags.album);
	free(afhi->tags.comment);
}

static inline uint32_t get_chunk_len(long unsigned chunk_num,
		const struct afh_info *afhi)
{
	return afhi->chunk_table[chunk_num + 1] - afhi->chunk_table[chunk_num];
}

/**
 * Get one chunk of audio data.
 *
 * This implicitly calls \ref audio_format_handler::open at the first call.
 *
 * \param chunk_num The number of the chunk to get.
 * \param afhi As returned from \ref audio_format_handler::get_file_info().
 * \param audio_format_id Determines the audio format handler to use.
 * \param map The memory mapped audio file.
 * \param mapsize Passed to \ref audio_format_handler::open().
 * \param buf Result pointer.
 * \param len The length of the chunk in bytes.
 * \param afh_context Value/result, determines whether ->open() is called.
 *
 * \return Standard. On success, the buffer pointer points to a chunk of
 * memory inside of the memory mapping. It must not be freed by the caller.
 */
__must_check int afh_get_chunk(long unsigned chunk_num, struct afh_info *afhi,
		uint8_t audio_format_id, const void *map, size_t mapsize,
		const char **buf, uint32_t *len, void **afh_context)
{
	struct audio_format_handler *afh = afl[audio_format_id];

	if (afh_supports_dynamic_chunks(audio_format_id)) {
		int ret;

		if (!*afh_context) {
			ret = afh->open(map, mapsize, afh_context);
			if (ret < 0)
				return ret;
		}
		ret = afh->get_chunk(chunk_num, *afh_context,
			buf, len);
		if (ret < 0) {
			afh->close(*afh_context);
			*afh_context = NULL;
		}
		return ret;
	} else {
		size_t pos = afhi->chunk_table[chunk_num];
		*buf = map + pos;
		*len = get_chunk_len(chunk_num, afhi);
		return 0;
	}
}

/**
 * Deallocate resources (dynamic chunk handling only).
 *
 * This function should be called if \ref afh_get_chunk() was called at
 * least once. It is OK to call it even for audio formats which do not
 * support dynamic chunks, in which case the function does nothing.
 *
 * \param afh_context As returned from \ref audio_format_handler::open().
 * \param audio_format_id Determines the audio format handler to use.
 */
void afh_close(void *afh_context, uint8_t audio_format_id)
{
	struct audio_format_handler *afh = afl[audio_format_id];

	if (!afh_supports_dynamic_chunks(audio_format_id))
		return;
	if (!afh->close)
		return;
	if (!afh_context)
		return;
	afh->close(afh_context);
}

/**
 * Find a suitable start chunk.
 *
 * \param approx_chunk_num Upper bound for the chunk number to return.
 * \param afhi Needed for the chunk table.
 * \param audio_format_id Determines the afh.
 *
 * \return For audio format handlers which support dynamic chunks, the function
 * returns the given chunk number. Otherwise it returns the first non-empty
 * chunk <= approx_chunk_num.
 *
 * \sa \ref afh_get_chunk().
 */
int32_t afh_get_start_chunk(int32_t approx_chunk_num,
		const struct afh_info *afhi, uint8_t audio_format_id)
{
	int32_t k;

	if (afh_supports_dynamic_chunks(audio_format_id))
		return approx_chunk_num;

	for (k = PARA_MAX(0, approx_chunk_num); k >= 0; k--)
		if (get_chunk_len(k, afhi) > 0)
			return k;
	return 0;
}

/**
 * Get the header of an audio file.
 *
 * \param afhi The audio file handler data describing the file.
 * \param audio_format_id Determines the audio format handler.
 * \param map The data of the audio file.
 * \param mapsize The number of bytes of the mapped audio file.
 * \param buf Result: Points to a buffer containing the header on return.
 * \param len Result: The length of the header is stored here.
 *
 * This function sets the buffer pointer to NULL and the length to zero if
 * either input pointer is NULL, if the map size is zero or if the audio
 * format does not need special header treatment.
 *
 * Otherwise, if the audio format handler defines \ref
 * audio_format_handler::get_header(), this method is called to obtain the
 * header. Otherwise a reference to the first chunk is returned.
 *
 * Once the header is no longer needed, the caller must call \ref
 * afh_free_header() to free the resources allocated by this function.
 */
void afh_get_header(struct afh_info *afhi, uint8_t audio_format_id,
		void *map, size_t mapsize, char **buf, size_t *len)
{
	struct audio_format_handler *afh = afl[audio_format_id];

	if (!map || !afhi || !afhi->header_len) {
		*buf = NULL;
		*len = 0;
		return;
	}
	if (!afh->get_header) {
		*len = afhi->header_len;
		*buf = map;
		return;
	}
	afh->get_header(map, mapsize, buf, len);
}

/**
 * Deallocate any resources obtained from afh_get_header().
 *
 * \param header_buf Pointer obtained via afh_get_header().
 * \param audio_format_id Determines the audio format handler.
 */
void afh_free_header(char *header_buf, uint8_t audio_format_id)
{
	struct audio_format_handler *afh = afl[audio_format_id];

	if (afh->get_header)
		free(header_buf);
}

/**
 * Pretty-print the contents of a struct \ref afh_info into a buffer.
 *
 * \param audio_format_num The audio format number.
 * \param afhi Pointer to the structure that contains the information.
 * \param result Return pointer.
 *
 * The result buffer is dynamically allocated and should be freed by the
 * caller.
 *
 * \return The number of bytes. This function never fails.
 */
unsigned afh_get_afhi_txt(int audio_format_num, struct afh_info *afhi, char **result)
{
	return xasprintf(result, "%s: %dkbit/s\n" /* bitrate */
		"%s: %s\n" /* format */
		"%s: %dHz\n" /* frequency */
		"%s: %d\n" /* channels */
		"%s: %" PRIu32 "\n" /* seconds total */
		"%s: %lu: %lu\n" /* chunk time */
		"%s: %" PRIu32 "\n" /* num chunks */
		"%s: %" PRIu32 "\n" /* max chunk size */
		"%s: %s\n" /* techinfo */
		"%s: %s\n" /* artist */
		"%s: %s\n" /* title */
		"%s: %s\n" /* year */
		"%s: %s\n" /* album */
		"%s: %s\n", /* comment */
		status_item_list[SI_bitrate], afhi->bitrate,
		status_item_list[SI_format], audio_format_name(audio_format_num),
		status_item_list[SI_frequency], afhi->frequency,
		status_item_list[SI_channels], afhi->channels,
		status_item_list[SI_seconds_total], afhi->seconds_total,
		status_item_list[SI_chunk_time], (long unsigned)afhi->chunk_tv.tv_sec,
			(long unsigned)afhi->chunk_tv.tv_usec,
		status_item_list[SI_num_chunks], afhi->chunks_total,
		status_item_list[SI_max_chunk_size], afhi->max_chunk_size,
		status_item_list[SI_techinfo], afhi->techinfo? afhi->techinfo : "",
		status_item_list[SI_artist], afhi->tags.artist? afhi->tags.artist : "",
		status_item_list[SI_title], afhi->tags.title? afhi->tags.title : "",
		status_item_list[SI_year], afhi->tags.year? afhi->tags.year : "",
		status_item_list[SI_album], afhi->tags.album? afhi->tags.album : "",
		status_item_list[SI_comment], afhi->tags.comment? afhi->tags.comment : ""
	);
}

/**
 * Determine the maximal chunk size by iterating the chunk table.
 *
 * \param afhi Value/result.
 *
 * This function is called by the audio format handlers, for example when a
 * new audio file is added to the afs database. The chunk table is determined
 * from the given afhi pointer, and the maximal chunk size is returned via
 * the ->max_chunk_size member of the same pointer.
 */
void set_max_chunk_size(struct afh_info *afhi)
{
	uint32_t n, max = 0, old = 0;

	for (n = 0; n <= afhi->chunks_total; n++) {
		uint32_t val = afhi->chunk_table[n];
		/*
		 * If the first chunk is the header, do not consider it for the
		 * calculation of the largest chunk size.
		 */
		if (n == 0 || (n == 1 && afhi->header_len > 0)) {
			old = val;
			continue;
		}
		max = PARA_MAX(max, val - old);
		old = val;
	}
	afhi->max_chunk_size = max;
}

/**
 * Create a copy of the given file with altered meta tags.
 *
 * \param audio_format_id Determines which audio format handler to use.
 * \param map The (read-only) memory map of the input file.
 * \param mapsize The size of the input file in bytes.
 * \param tags The new tags.
 * \param output_fd Altered file is created using this file descriptor.
 *
 * This simply calls the ->rewrite_tags() method of the audio format handler
 * associated with the given ID, passing the remaining arguments verbatim.
 *
 * \return The return value of the underlying call to \ref
 * audio_format_handler::rewrite_tags().
 */
int afh_rewrite_tags(int audio_format_id, void *map, size_t mapsize,
		struct taginfo *tags, int output_fd)
{
	struct audio_format_handler *afh = afl[audio_format_id];
	return afh->rewrite_tags(map, mapsize, tags, output_fd);
}