#include "tool_set_timezone.h"
#include "mimi_config.h"

#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#include <time.h>
#include "esp_log.h"
#include "nvs.h"
#include "cJSON.h"

static const char *TAG = "tool_timezone";

/* Common timezone mappings for user-friendly names */
typedef struct {
    const char *name;
    const char *posix_tz;
} tz_mapping_t;

static const tz_mapping_t tz_mappings[] = {
    { "Asia/Shanghai", "CST-8" },
    { "Asia/Beijing", "CST-8" },
    { "Asia/Hong_Kong", "HKT-8" },
    { "Asia/Tokyo", "JST-9" },
    { "Asia/Seoul", "KST-9" },
    { "Asia/Singapore", "SGT-8" },
    { "Asia/Kolkata", "IST-5:30" },
    { "Asia/Dubai", "GST-4" },
    { "Europe/London", "GMT0BST,M3.5.0/1,M10.5.0" },
    { "Europe/Paris", "CET-1CEST,M3.5.0,M10.5.0/3" },
    { "Europe/Berlin", "CET-1CEST,M3.5.0,M10.5.0/3" },
    { "America/New_York", "EST5EDT,M3.2.0,M11.1.0" },
    { "America/Chicago", "CST6CDT,M3.2.0,M11.1.0" },
    { "America/Denver", "MST7MDT,M3.2.0,M11.1.0" },
    { "America/Los_Angeles", "PST8PDT,M3.2.0,M11.1.0" },
    { "Australia/Sydney", "AEST-10AEDT,M10.1.0,M4.1.0/3" },
    { "UTC", "UTC0" },
    { "GMT", "GMT0" },
};

static const char *resolve_timezone(const char *tz_str)
{
    if (!tz_str || !tz_str[0]) return NULL;

    for (size_t i = 0; i < sizeof(tz_mappings) / sizeof(tz_mappings[0]); i++) {
        if (strcmp(tz_str, tz_mappings[i].name) == 0) {
            return tz_mappings[i].posix_tz;
        }
    }

    return tz_str;
}

static bool validate_timezone(const char *tz_str)
{
    if (!tz_str || !tz_str[0]) return false;
    if (strlen(tz_str) > 64) return false;

    for (size_t i = 0; i < sizeof(tz_mappings) / sizeof(tz_mappings[0]); i++) {
        if (strcmp(tz_str, tz_mappings[i].name) == 0) return true;
    }

    if (strchr(tz_str, '+') || strchr(tz_str, '-') ||
        strcmp(tz_str, "UTC0") == 0 || strcmp(tz_str, "GMT0") == 0) {
        return true;
    }

    return false;
}

static esp_err_t save_timezone_nvs(const char *tz_str)
{
    nvs_handle_t nvs;
    esp_err_t err = nvs_open("system_config", NVS_READWRITE, &nvs);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to open NVS: %s", esp_err_to_name(err));
        return err;
    }

    err = nvs_set_str(nvs, MIMI_NVS_KEY_TIMEZONE, tz_str);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to save timezone: %s", esp_err_to_name(err));
        nvs_close(nvs);
        return err;
    }

    err = nvs_commit(nvs);
    nvs_close(nvs);

    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to commit NVS: %s", esp_err_to_name(err));
        return err;
    }

    return ESP_OK;
}

esp_err_t tool_set_timezone_execute(const char *input_json, char *output, size_t output_size)
{
    ESP_LOGI(TAG, "Setting timezone...");

    cJSON *root = cJSON_Parse(input_json);
    if (!root) {
        snprintf(output, output_size, "Error: invalid JSON input");
        return ESP_ERR_INVALID_ARG;
    }

    cJSON *tz_item = cJSON_GetObjectItem(root, "timezone");
    if (!tz_item || !cJSON_IsString(tz_item)) {
        cJSON_Delete(root);
        snprintf(output, output_size, "Error: 'timezone' field required (string)");
        return ESP_ERR_INVALID_ARG;
    }

    const char *input_tz = tz_item->valuestring;
    const char *resolved_tz = resolve_timezone(input_tz);

    if (!resolved_tz || !validate_timezone(resolved_tz)) {
        cJSON_Delete(root);
        snprintf(output, output_size, "Error: invalid timezone format '%s'. Use POSIX format (e.g. CST-8) or city name (e.g. Asia/Shanghai)", input_tz);
        return ESP_ERR_INVALID_ARG;
    }

    esp_err_t err = save_timezone_nvs(resolved_tz);
    if (err != ESP_OK) {
        cJSON_Delete(root);
        snprintf(output, output_size, "Error: failed to save timezone (%s)", esp_err_to_name(err));
        return err;
    }

    setenv("TZ", resolved_tz, 1);
    tzset();

    time_t now = time(NULL);
    struct tm tm_now;
    localtime_r(&now, &tm_now);
    char time_str[64];
    strftime(time_str, sizeof(time_str), "%Y-%m-%d %H:%M:%S %Z", &tm_now);

    cJSON_Delete(root);
    snprintf(output, output_size, "Timezone set to '%s'. Current time: %s", resolved_tz, time_str);
    ESP_LOGI(TAG, "Timezone set to: %s, current time: %s", resolved_tz, time_str);

    return ESP_OK;
}