/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_config.h"

#ifndef SDL_POWER_DISABLED
#if SDL_POWER_LINUX

#include <stdio.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <fcntl.h>

#include "SDL_power.h"

static const char *proc_apm_path = "/proc/apm";
static const char *proc_acpi_battery_path = "/proc/acpi/battery";
static const char *proc_acpi_ac_adapter_path = "/proc/acpi/ac_adapter";

static int open_acpi_file(const char *base, const char *node, const char *key)
{
    const size_t pathlen = strlen(base) + strlen(node) + strlen(key) + 3;
    char *path = (char *) alloca(pathlen);
    if (path == NULL) {
        return -1;  /* oh well. */
    }

    snprintf(path, pathlen, "%s/%s/%s", base, node, key);
    return open(path, O_RDONLY);
}


static SDL_bool
load_acpi_file(const char *base, const char *node, const char *key,
               char *buf, size_t buflen)
{
    ssize_t br = 0;
    const int fd = open_acpi_file(base, node, key);
    if (fd == -1) {
        return SDL_FALSE;
    }
    br = read(fd, buf, buflen-1);
    close(fd);
    if (br < 0) {
        return SDL_FALSE;
    }
    buf[br] = '\0';             // null-terminate the string.
    return SDL_TRUE;
}


static SDL_bool
make_proc_acpi_key_val(char **_ptr, char **_key, char **_val)
{
    char *ptr = *_ptr;

    while (*ptr == ' ') {
        ptr++;  /* skip whitespace. */
    }

    if (*ptr == '\0') {
        return SDL_FALSE;  /* EOF. */
    }

    *_key = ptr;

    while ((*ptr != ':') && (*ptr != '\0')) {
        ptr++;
    }

    if (*ptr == '\0') {
        return SDL_FALSE;  /* (unexpected) EOF. */
    }

    *(ptr++) = '\0';  /* terminate the key. */

    while ((*ptr == ' ') && (*ptr != '\0')) {
        ptr++;  /* skip whitespace. */
    }

    if (*ptr == '\0') {
        return SDL_FALSE;  /* (unexpected) EOF. */
    }

    *_val = ptr;

    while ((*ptr != '\n') && (*ptr != '\0')) {
        ptr++;
    }

    if (*ptr != '\0') {
        *(ptr++) = '\0';  /* terminate the value. */
    }

    *_ptr = ptr;  /* store for next time. */
    return SDL_TRUE;
}

static void
check_proc_acpi_battery(const char * node, SDL_bool * have_battery,
                        SDL_bool * charging, int *seconds, int *percent)
{
    const char *base = proc_acpi_battery_path;
    char info[1024];
    char state[1024];
    char *ptr = NULL;
    char *key = NULL;
    char *val = NULL;
    SDL_bool charge = SDL_FALSE;
    SDL_bool choose = SDL_FALSE;
    int maximum = -1;
    int remaining = -1;
    int secs = -1;
    int pct = -1;

    if (!load_acpi_file(base, node, "state", state, sizeof (state))) {
        return;
    } else if (!load_acpi_file(base, node, "info", info, sizeof (info))) {
        return;
    }

    ptr = &state[0];
    while (make_proc_acpi_key_val(&ptr, &key, &val)) {
        if (strcmp(key, "present") == 0) {
            if (strcmp(val, "yes") == 0) {
                *have_battery = SDL_TRUE;
            }
        } else if (strcmp(key, "charging state") == 0) {
            /* !!! FIXME: what exactly _does_ charging/discharging mean? */
            if (strcmp(val, "charging/discharging") == 0) {
                charge = SDL_TRUE;
            } else if (strcmp(val, "charging") == 0) {
                charge = SDL_TRUE;
            }
        } else if (strcmp(key, "remaining capacity") == 0) {
            char *endptr = NULL;
            const int cvt = (int) strtol(val, &endptr, 10);
            if (*endptr == ' ') {
                remaining = cvt;
            }
        }
    }

    ptr = &info[0];
    while (make_proc_acpi_key_val(&ptr, &key, &val)) {
        if (strcmp(key, "design capacity") == 0) {
            char *endptr = NULL;
            const int cvt = (int) strtol(val, &endptr, 10);
            if (*endptr == ' ') {
                maximum = cvt;
            }
        }
    }

    if ((maximum >= 0) && (remaining >= 0)) {
        pct = (int) ((((float) remaining) / ((float) maximum)) * 100.0f);
        if (pct < 0) {
            pct = 0;
        } else if (pct > 100) {
            pct = 100;
        }
    }

    /* !!! FIXME: calculate (secs). */

    /*
     * We pick the battery that claims to have the most minutes left.
     *  (failing a report of minutes, we'll take the highest percent.)
     */
    if ((secs < 0) && (*seconds < 0)) {
        if ((pct < 0) && (*percent < 0)) {
            choose = SDL_TRUE;  /* at least we know there's a battery. */
        }
        if (pct > *percent) {
            choose = SDL_TRUE;
        }
    } else if (secs > *seconds) {
        choose = SDL_TRUE;
    }

    if (choose) {
        *seconds = secs;
        *percent = pct;
        *charging = charge;
    }
}

static void
check_proc_acpi_ac_adapter(const char * node, SDL_bool * have_ac)
{
    const char *base = proc_acpi_ac_adapter_path;
    char state[256];
    char *ptr = NULL;
    char *key = NULL;
    char *val = NULL;

    if (!load_acpi_file(base, node, "state", state, sizeof (state))) {
        return;
    }

    ptr = &state[0];
    while (make_proc_acpi_key_val(&ptr, &key, &val)) {
        if (strcmp(key, "state") == 0) {
            if (strcmp(val, "on-line") == 0) {
                *have_ac = SDL_TRUE;
            }
        }
    }
}


SDL_bool
SDL_GetPowerInfo_Linux_proc_acpi(SDL_PowerState * state,
                                 int *seconds, int *percent)
{
    struct dirent *dent = NULL;
    DIR *dirp = NULL;
    SDL_bool have_battery = SDL_FALSE;
    SDL_bool have_ac = SDL_FALSE;
    SDL_bool charging = SDL_FALSE;

    *seconds = -1;
    *percent = -1;
    *state = SDL_POWERSTATE_UNKNOWN;

    dirp = opendir(proc_acpi_battery_path);
    if (dirp == NULL) {
        return SDL_FALSE;  /* can't use this interface. */
    } else {
        while ((dent = readdir(dirp)) != NULL) {
            const char *node = dent->d_name;
            check_proc_acpi_battery(node, &have_battery, &charging,
                                    seconds, percent);
        }
        closedir(dirp);
    }

    dirp = opendir(proc_acpi_ac_adapter_path);
    if (dirp == NULL) {
        return SDL_FALSE;  /* can't use this interface. */
    } else {
        while ((dent = readdir(dirp)) != NULL) {
            const char *node = dent->d_name;
            check_proc_acpi_ac_adapter(node, &have_ac);
        }
        closedir(dirp);
    }

    if (!have_battery) {
        *state = SDL_POWERSTATE_NO_BATTERY;
    } else if (charging) {
        *state = SDL_POWERSTATE_CHARGING;
    } else if (have_ac) {
        *state = SDL_POWERSTATE_CHARGED;
    } else {
        *state = SDL_POWERSTATE_ON_BATTERY;
    }

    return SDL_TRUE;   /* definitive answer. */
}


static SDL_bool
next_string(char **_ptr, char **_str)
{
    char *ptr = *_ptr;
    char *str = *_str;

    while (*ptr == ' ') {       /* skip any spaces... */
        ptr++;
    }

    if (*ptr == '\0') {
        return SDL_FALSE;
    }

    str = ptr;
    while ((*ptr != ' ') && (*ptr != '\n') && (*ptr != '\0'))
        ptr++;

    if (*ptr != '\0')
        *(ptr++) = '\0';

    *_str = str;
    *_ptr = ptr;
    return SDL_TRUE;
}

static SDL_bool
int_string(char *str, int *val)
{
    char *endptr = NULL;
    *val = (int) strtol(str, &endptr, 0);
    return ((*str != '\0') && (*endptr == '\0'));
}

/* http://lxr.linux.no/linux+v2.6.29/drivers/char/apm-emulation.c */
SDL_bool
SDL_GetPowerInfo_Linux_proc_apm(SDL_PowerState * state,
                                int *seconds, int *percent)
{
    SDL_bool need_details = SDL_FALSE;
    int ac_status = 0;
    int battery_status = 0;
    int battery_flag = 0;
    int battery_percent = 0;
    int battery_time = 0;
    const int fd = open(proc_apm_path, O_RDONLY);
    char buf[128];
    char *ptr = &buf[0];
    char *str = NULL;
    ssize_t br;

    if (fd == -1) {
        return SDL_FALSE;       /* can't use this interface. */
    }

    br = read(fd, buf, sizeof (buf) - 1);
    close(fd);

    if (br < 0) {
        return SDL_FALSE;
    }

    buf[br] = '\0';             // null-terminate the string.
    if (!next_string(&ptr, &str)) {     /* driver version */
        return SDL_FALSE;
    }
    if (!next_string(&ptr, &str)) {     /* BIOS version */
        return SDL_FALSE;
    }
    if (!next_string(&ptr, &str)) {     /* APM flags */
        return SDL_FALSE;
    }

    if (!next_string(&ptr, &str)) {     /* AC line status */
        return SDL_FALSE;
    } else if (!int_string(str, &ac_status)) {
        return SDL_FALSE;
    }

    if (!next_string(&ptr, &str)) {     /* battery status */
        return SDL_FALSE;
    } else if (!int_string(str, &battery_status)) {
        return SDL_FALSE;
    }
    if (!next_string(&ptr, &str)) {     /* battery flag */
        return SDL_FALSE;
    } else if (!int_string(str, &battery_flag)) {
        return SDL_FALSE;
    }
    if (!next_string(&ptr, &str)) {     /* remaining battery life percent */
        return SDL_FALSE;
    }
    if (str[strlen(str) - 1] == '%') {
        str[strlen(str) - 1] = '\0';
    }
    if (!int_string(str, &battery_percent)) {
        return SDL_FALSE;
    }

    if (!next_string(&ptr, &str)) {     /* remaining battery life time */
        return SDL_FALSE;
    } else if (!int_string(str, &battery_time)) {
        return SDL_FALSE;
    }

    if (!next_string(&ptr, &str)) {     /* remaining battery life time units */
        return SDL_FALSE;
    } else if (strcmp(str, "min") == 0) {
        battery_time *= 60;
    }

    if (battery_flag == 0xFF) { /* unknown state */
        *state = SDL_POWERSTATE_UNKNOWN;
    } else if (battery_flag & (1 << 7)) {       /* no battery */
        *state = SDL_POWERSTATE_NO_BATTERY;
    } else if (battery_flag & (1 << 3)) {       /* charging */
        *state = SDL_POWERSTATE_CHARGING;
        need_details = SDL_TRUE;
    } else if (ac_status == 1) {
        *state = SDL_POWERSTATE_CHARGED;        /* on AC, not charging. */
        need_details = SDL_TRUE;
    } else {
        *state = SDL_POWERSTATE_ON_BATTERY;
        need_details = SDL_TRUE;
    }

    *percent = -1;
    *seconds = -1;
    if (need_details) {
        const int pct = battery_percent;
        const int secs = battery_time;

        if (pct >= 0) {         /* -1 == unknown */
            *percent = (pct > 100) ? 100 : pct; /* clamp between 0%, 100% */
        }
        if (secs >= 0) {        /* -1 == unknown */
            *seconds = secs;
        }
    }

    return SDL_TRUE;
}

#endif /* SDL_POWER_LINUX */
#endif /* SDL_POWER_DISABLED */

/* vi: set ts=4 sw=4 expandtab: */
