/*
 * This file is part of mpv.
 *
 * mpv is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * mpv is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <string.h>
#include <stdio.h>
#include <math.h>
#include <assert.h>

#include <libavutil/common.h>

#include "config.h"
#include "audio/out/ao.h"
#include "audio/filter/af.h"
#include "common/global.h"
#include "common/msg.h"
#include "talloc.h"
#include "mixer.h"

struct mixer {
    struct mp_log *log;
    struct MPOpts *opts;
    struct ao *ao;
    struct af_stream *af;
    // Static, dependent on ao/softvol settings
    bool softvol;                       // use AO (false) or af_volume (true)
    bool persistent_volume;             // volume does not need to be restored
    bool emulate_mute;                  // if true, emulate mute with volume=0
    // Last known values (possibly out of sync with reality)
    float vol_l, vol_r;
    bool muted;
    // Used to decide whether we should unmute on uninit
    bool muted_by_us;
    /* Contains ao driver name or "softvol" if volume is not persistent
     * and needs to be restored after the driver is reinitialized. */
    const char *driver;
    // Other stuff
    float balance;
};

struct mixer *mixer_init(void *talloc_ctx, struct mpv_global *global)
{
    struct mixer *mixer = talloc_ptrtype(talloc_ctx, mixer);
    *mixer = (struct mixer) {
        .log = mp_log_new(mixer, global->log, "mixer"),
        .opts = global->opts,
        .vol_l = 100,
        .vol_r = 100,
        .driver = "",
    };
    return mixer;
}

bool mixer_audio_initialized(struct mixer *mixer)
{
    return !!mixer->ao;
}

float mixer_getmaxvolume(struct mixer *mixer)
{
    // gain == 1
    return mixer->softvol ? mixer->opts->softvol_max : 100;
}

static void checkvolume(struct mixer *mixer)
{
    if (!mixer->ao)
        return;

    ao_control_vol_t vol = {mixer->vol_l, mixer->vol_r};
    if (mixer->softvol) {
        float gain;
        if (!af_control_any_rev(mixer->af, AF_CONTROL_GET_VOLUME, &gain))
            gain = 1.0;
        vol.left = gain * 100.0;
        vol.right = gain * 100.0;
    } else {
        MP_DBG(mixer, "Reading volume from AO.\n");
        // Rely on the values not changing if the query is not supported
        ao_control(mixer->ao, AOCONTROL_GET_VOLUME, &vol);
        ao_control(mixer->ao, AOCONTROL_GET_MUTE, &mixer->muted);
    }
    float l = mixer->vol_l;
    float r = mixer->vol_r;
    if (mixer->emulate_mute && mixer->muted)
        l = r = 0;
    /* Try to detect cases where the volume has been changed by some external
     * action (such as something else changing a shared system-wide volume).
     * We don't test for exact equality, as some AOs may round the value
     * we last set to some nearby supported value. 3 has been the default
     * volume step for increase/decrease keys, and is apparently big enough
     * to step to the next possible value in most setups.
     */
    if (FFABS(vol.left - l) >= 3 || FFABS(vol.right - r) >= 3) {
        mixer->vol_l = vol.left;
        mixer->vol_r = vol.right;
        if (mixer->emulate_mute)
            mixer->muted = false;
    }
    mixer->muted_by_us &= mixer->muted;
}

void mixer_getvolume(struct mixer *mixer, float *l, float *r)
{
    checkvolume(mixer);
    *l = mixer->vol_l;
    *r = mixer->vol_r;
}

static void setvolume_internal(struct mixer *mixer, float l, float r)
{
    if (!mixer->softvol) {
        MP_DBG(mixer, "Setting volume on AO.\n");
        struct ao_control_vol vol = {.left = l, .right = r};
        if (ao_control(mixer->ao, AOCONTROL_SET_VOLUME, &vol) != CONTROL_OK)
            MP_ERR(mixer, "Failed to change audio output volume.\n");
        return;
    }
    float gain = (l + r) / 2.0 / 100.0;
    if (!af_control_any_rev(mixer->af, AF_CONTROL_SET_VOLUME, &gain)) {
        if (gain == 1.0)
            return;
        MP_VERBOSE(mixer, "Inserting volume filter.\n");
        if (!(af_add(mixer->af, "volume", "softvol", NULL)
              && af_control_any_rev(mixer->af, AF_CONTROL_SET_VOLUME, &gain)))
            MP_ERR(mixer, "No volume control available.\n");
    }
}

void mixer_setvolume(struct mixer *mixer, float l, float r)
{
    checkvolume(mixer);  // to check mute status

    float max = mixer_getmaxvolume(mixer);
    mixer->vol_l = MPCLAMP(l, 0, max);
    mixer->vol_r = MPCLAMP(r, 0, max);
    if (mixer->ao && !(mixer->emulate_mute && mixer->muted))
        setvolume_internal(mixer, mixer->vol_l, mixer->vol_r);
}

void mixer_getbothvolume(struct mixer *mixer, float *b)
{
    float mixer_l, mixer_r;
    mixer_getvolume(mixer, &mixer_l, &mixer_r);
    *b = (mixer_l + mixer_r) / 2;
}

void mixer_setmute(struct mixer *mixer, bool mute)
{
    checkvolume(mixer);
    if (mute == mixer->muted)
        return;
    if (mixer->ao) {
        mixer->muted = mute;
        mixer->muted_by_us = mute;
        if (mixer->emulate_mute) {
            setvolume_internal(mixer, mixer->vol_l*!mute, mixer->vol_r*!mute);
        } else {
            ao_control(mixer->ao, AOCONTROL_SET_MUTE, &mute);
        }
        checkvolume(mixer);
    } else {
        mixer->muted = mute;
        mixer->muted_by_us = mute;
    }
}

bool mixer_getmute(struct mixer *mixer)
{
    checkvolume(mixer);
    return mixer->muted;
}

void mixer_addvolume(struct mixer *mixer, float step)
{
    float vol_l, vol_r;
    mixer_getvolume(mixer, &vol_l, &vol_r);
    mixer_setvolume(mixer, vol_l + step, vol_r + step);
}

void mixer_getbalance(struct mixer *mixer, float *val)
{
    if (mixer->af)
        af_control_any_rev(mixer->af, AF_CONTROL_GET_PAN_BALANCE, &mixer->balance);
    *val = mixer->balance;
}

/* NOTE: Currently the balance code is seriously buggy: it always changes
 * the af_pan mapping between the first two input channels and first two
 * output channels to particular values. These values make sense for an
 * af_pan instance that was automatically inserted for balance control
 * only and is otherwise an identity transform, but if the filter was
 * there for another reason, then ignoring and overriding the original
 * values is completely wrong.
 */

void mixer_setbalance(struct mixer *mixer, float val)
{
    struct af_instance *af_pan_balance;

    mixer->balance = val;

    if (!mixer->af)
        return;

    if (af_control_any_rev(mixer->af, AF_CONTROL_SET_PAN_BALANCE, &val))
        return;

    if (val == 0)
        return;

    if (!(af_pan_balance = af_add(mixer->af, "pan", "autopan", NULL))) {
        MP_ERR(mixer, "No balance control available.\n");
        return;
    }

    /* make all other channels pass through since by default pan blocks all */
    for (int i = 2; i < AF_NCH; i++) {
        float level[AF_NCH] = {0};
        level[i] = 1.f;
        af_control_ext_t arg_ext = { .ch = i, .arg = level };
        af_pan_balance->control(af_pan_balance, AF_CONTROL_SET_PAN_LEVEL,
                                &arg_ext);
    }

    af_pan_balance->control(af_pan_balance, AF_CONTROL_SET_PAN_BALANCE, &val);
}

char *mixer_get_volume_restore_data(struct mixer *mixer)
{
    if (!mixer->driver[0])
        return NULL;
    return talloc_asprintf(NULL, "%s:%f:%f:%d", mixer->driver, mixer->vol_l,
                           mixer->vol_r, mixer->muted_by_us);
}

static void probe_softvol(struct mixer *mixer)
{
    bool ao_perapp = ao_control(mixer->ao, AOCONTROL_HAS_PER_APP_VOLUME, 0) == 1;
    bool ao_softvol = ao_control(mixer->ao, AOCONTROL_HAS_SOFT_VOLUME, 0) == 1;
    assert(!(ao_perapp && ao_softvol));
    mixer->persistent_volume = !ao_softvol;

    if (mixer->opts->softvol == SOFTVOL_AUTO) {
        // No system-wide volume => fine with AO volume control.
        mixer->softvol = !ao_softvol && !ao_perapp;
    } else {
        mixer->softvol = mixer->opts->softvol == SOFTVOL_YES;
    }

    if (mixer->softvol)
        mixer->persistent_volume = false;

    MP_DBG(mixer, "Will use af_volume: %s\n", mixer->softvol ? "yes" : "no");

    // If we can't use real volume control => force softvol.
    if (!mixer->softvol) {
        ao_control_vol_t vol;
        if (ao_control(mixer->ao, AOCONTROL_GET_VOLUME, &vol) != CONTROL_OK) {
            mixer->softvol = true;
            MP_WARN(mixer, "Hardware volume control unavailable.\n");
        }
    }

    // Probe native mute support.
    mixer->emulate_mute = true;
    if (!mixer->softvol) {
        if (ao_control(mixer->ao, AOCONTROL_GET_MUTE, &(bool){0}) == CONTROL_OK)
            mixer->emulate_mute = false;
    }
}

static void restore_volume(struct mixer *mixer)
{
    struct MPOpts *opts = mixer->opts;
    struct ao *ao = mixer->ao;

    float force_vol_l = -1, force_vol_r = -1;
    int force_mute = -1;

    const char *prev_driver = mixer->driver;
    mixer->driver = mixer->softvol ? "softvol" : ao_get_name(ao);

    // Restore old parameters if volume won't survive reinitialization.
    // But not if volume scale is possibly different.
    if (!mixer->persistent_volume && strcmp(mixer->driver, prev_driver) == 0) {
        force_vol_l = mixer->vol_l;
        force_vol_r = mixer->vol_r;
    }

    // Set mute if we disabled it on uninit last time.
    if (mixer->muted_by_us)
        force_mute = 1;

    // Set parameters from command line.
    if (opts->mixer_init_volume >= 0)
        force_vol_l = force_vol_r = opts->mixer_init_volume;
    if (opts->mixer_init_mute >= 0)
        force_mute = opts->mixer_init_mute;

    // Set parameters from playback resume.
    char *data = mixer->opts->mixer_restore_volume_data;
    if (!mixer->persistent_volume && data && data[0]) {
        char drv[40];
        float v_l, v_r;
        int m;
        if (sscanf(data, "%39[^:]:%f:%f:%d", drv, &v_l, &v_r, &m) == 5) {
            if (strcmp(mixer->driver, drv) == 0) {
                force_vol_l = v_l;
                force_vol_r = v_r;
                force_mute = !!m;
                MP_DBG(mixer, "Restoring volume from resume config.\n");
            }
        }
        talloc_free(mixer->opts->mixer_restore_volume_data);
        mixer->opts->mixer_restore_volume_data = NULL;
    }

    // Using --volume should not reset the volume on every file (i.e. reinit),
    // OTOH mpv --{ --volume 10 f1.mkv --} --{ --volume 20 f2.mkv --} must work.
    // Resetting the option volumes to "auto" (-1) is easiest. If file local
    // options (as shown above) are used, the option handler code will reset
    // them to other values, and force the volume to be reset as well.
    opts->mixer_init_volume = -1;
    opts->mixer_init_mute = -1;

    checkvolume(mixer);
    if (force_vol_l >= 0 && force_vol_r >= 0) {
        MP_DBG(mixer, "Restoring previous volume.\n");
        mixer_setvolume(mixer, force_vol_l, force_vol_r);
    }
    if (force_mute >= 0) {
        MP_DBG(mixer, "Restoring previous mute toggle.\n");
        mixer_setmute(mixer, force_mute);
    }
}

// Called after the audio filter chain is built or rebuilt.
// (Can be called multiple times, even without mixer_uninit() in-between.)
void mixer_reinit_audio(struct mixer *mixer, struct ao *ao, struct af_stream *af)
{
    if (!ao || !af)
        return;
    mixer->ao = ao;
    mixer->af = af;

    MP_DBG(mixer, "Reinit...\n");

    probe_softvol(mixer);
    restore_volume(mixer);

    if (mixer->balance != 0)
        mixer_setbalance(mixer, mixer->balance);
}

/* Called before uninitializing the audio filter chain. The main purpose is to
 * turn off mute, in case it's a global/persistent setting which might
 * otherwise be left enabled even after this player instance exits.
 */
void mixer_uninit_audio(struct mixer *mixer)
{
    if (!mixer->ao)
        return;

    MP_DBG(mixer, "Uninit...\n");

    checkvolume(mixer);
    if (mixer->muted_by_us && mixer->persistent_volume) {
        MP_DBG(mixer, "Draining.\n");
        /* Current audio output API combines playing the remaining buffered
         * audio and uninitializing the AO into one operation, even though
         * ideally unmute would happen between those two steps. We can't do
         * volume changes after uninitialization, but we don't want the
         * remaining audio to play at full volume either. Thus this
         * workaround to drop remaining audio first. */
        ao_reset(mixer->ao);
        mixer_setmute(mixer, false);
        /* We remember mute status and re-enable it if we play more audio
         * in the same process. */
        mixer->muted_by_us = true;
    }
    mixer->ao = NULL;
    mixer->af = NULL;
}