#include "battery.h"
#include "../util.h"

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

#define ADAPTER_BASE_PATH "/sys/class/power_supply/"
#define BATTERY_PATH "/sys/class/power_supply/BAT0"

static const char *adapter_search_names[] = {"AC0", "ADP1"};
static size_t adapter_search_names_count =
    sizeof(adapter_search_names) / sizeof(char *);
static char *adapter_status_path;
static int max_batery_charge;
static int show_notifiaction = TRUE;

static void find_max_battery_charge() {
    FILE *max_file = fopen(BATTERY_PATH "/charge_full", "r");
    fseeko(max_file, 0, SEEK_END);
    off_t len = ftello(max_file);
    rewind(max_file);
    char text[len + 1];
    text[len] = '\0';
    fread(text, 1, len, max_file);
    max_batery_charge = strtoul(text, NULL, 10);
    fclose(max_file);
}

static int is_battery_full() {
    FILE *status_file = fopen(BATTERY_PATH "/status", "r");
    if (!status_file) {
        return FALSE;
    }
    fseeko(status_file, 0, SEEK_END);
    off_t len = ftello(status_file);
    rewind(status_file);
    char status_text[len + 1];
    status_text[len] = '\0';
    fread(status_text, 1, len, status_file);
    fclose(status_file);
    return strcmp(status_text, "Full\n") == 0;
}

static int get_battery_percent() {
    if (is_battery_full()) {
        return 100;
    }
    FILE *battery_file = fopen(BATTERY_PATH "/charge_now", "r");
    if (!battery_file) {
        return -1;
    }
    fseeko(battery_file, 0, SEEK_END);
    off_t len = ftello(battery_file);
    rewind(battery_file);
    char charge_text[len + 1];
    charge_text[len] = '\0';
    fread(charge_text, 1, len, battery_file);
    fclose(battery_file);
    long charge = strtoul(charge_text, NULL, 10);
    float scale = (float)charge / (float)max_batery_charge;
    return round(scale * 100.0f);
}

static int is_adapter_connected() {
    FILE *adapter_file = fopen(adapter_status_path, "r");
    if (!adapter_file) {
        return -1;
    }
    char text[2] = {'\0', '\0'};
    fread(text, 1, 1, adapter_file);
    fclose(adapter_file);
    return text[0] == '1'; /* 1 means connected, anything else is not */
}

static void find_adapter_status_path() {
    size_t i;
    for (i = 0; i < adapter_search_names_count; ++i) {
        size_t name_len = strlen(adapter_search_names[i]);
        /* -1 is to compensate for '\0' at end of "/online" */
        char *name = qtb_malloc(sizeof(ADAPTER_BASE_PATH) + name_len + sizeof("/online") - 1);
        sprintf(name, "%s%s/online", ADAPTER_BASE_PATH, adapter_search_names[i]);
        FILE *file = fopen(name, "r");
        if (file) {
            adapter_status_path = name;
        } else {
            qtb_free(name);
        }
    }
}

void battery_module_init(void) {
    find_max_battery_charge();
    find_adapter_status_path();
}

static const char *get_battery_icon(int percent, int adapter) {
    if (adapter) {
        return "";
    } else if (percent <= 10) {
        return "";
    } else if (percent <= 20) {
        return "";
    } else if (percent <= 30) {
        return "";
    } else if (percent <= 40) {
        return "";
    } else if (percent <= 50) {
        return "";
    } else if (percent <= 60) {
        return "";
    } else if (percent <= 70) {
        return "";
    } else if (percent <= 90) {
        return "";
    } else if (percent < 100) {
        return "";
    } else {
        return "";
    }
}

static void warn_low_battery() {
#ifdef HAS_X11
    if (qtb_get_x_display()) { /* if x is running */
        system("notify-send -t 0 'Battery is less than 10%!'");
    } else {
#endif
        system("wall -t 0 'Battery is less than 10%!'");
#ifdef HAS_X11
    }
#endif
}

char *battery_module_poll() {
    char *output = qtb_calloc(16, 1);
    int percent = get_battery_percent();
    int adapter = is_adapter_connected();
    if (percent == -1 || adapter == -1) {
        sprintf(output, "？N/A%%");
    } else {
        const char *icon = get_battery_icon(percent, adapter);
        sprintf(output, "%s%3d%%", icon, percent);
        if (show_notifiaction && percent <= 10) {
            warn_low_battery();
            show_notifiaction = FALSE;
        } else if (percent > 10) {
            show_notifiaction = TRUE;
        }
    }
    return output;
}