#include "cron/cron_service.h"
#include "mimi_config.h"
#include "bus/message_bus.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "freertos/FreeRTOS.h"
#include "freertos/timers.h"
#include "esp_log.h"
#include "esp_random.h"
#include "cJSON.h"

static const char *TAG = "cron";

#define MAX_CRON_JOBS  MIMI_CRON_MAX_JOBS

static cron_job_t s_jobs[MAX_CRON_JOBS];
static int s_job_count = 0;
static TimerHandle_t s_cron_timer = NULL;

/* ── Persistence ──────────────────────────────────────────────── */

static void cron_generate_id(char *id_buf)
{
    uint32_t r = esp_random();
    snprintf(id_buf, 9, "%08x", (unsigned int)r);
}

static esp_err_t cron_load_jobs(void)
{
    FILE *f = fopen(MIMI_CRON_FILE, "r");
    if (!f) {
        ESP_LOGI(TAG, "No cron file found, starting fresh");
        s_job_count = 0;
        return ESP_OK;
    }

    /* Read entire file */
    fseek(f, 0, SEEK_END);
    long fsize = ftell(f);
    fseek(f, 0, SEEK_SET);

    if (fsize <= 0 || fsize > 8192) {
        ESP_LOGW(TAG, "Cron file invalid size: %ld", fsize);
        fclose(f);
        s_job_count = 0;
        return ESP_OK;
    }

    char *buf = malloc(fsize + 1);
    if (!buf) {
        fclose(f);
        return ESP_ERR_NO_MEM;
    }

    size_t n = fread(buf, 1, fsize, f);
    buf[n] = '\0';
    fclose(f);

    /* Parse JSON */
    cJSON *root = cJSON_Parse(buf);
    free(buf);

    if (!root) {
        ESP_LOGW(TAG, "Failed to parse cron JSON");
        s_job_count = 0;
        return ESP_OK;
    }

    cJSON *jobs_arr = cJSON_GetObjectItem(root, "jobs");
    if (!jobs_arr || !cJSON_IsArray(jobs_arr)) {
        cJSON_Delete(root);
        s_job_count = 0;
        return ESP_OK;
    }

    s_job_count = 0;
    cJSON *item;
    cJSON_ArrayForEach(item, jobs_arr) {
        if (s_job_count >= MAX_CRON_JOBS) break;

        cron_job_t *job = &s_jobs[s_job_count];
        memset(job, 0, sizeof(cron_job_t));

        const char *id = cJSON_GetStringValue(cJSON_GetObjectItem(item, "id"));
        const char *name = cJSON_GetStringValue(cJSON_GetObjectItem(item, "name"));
        const char *kind_str = cJSON_GetStringValue(cJSON_GetObjectItem(item, "kind"));
        const char *message = cJSON_GetStringValue(cJSON_GetObjectItem(item, "message"));
        const char *channel = cJSON_GetStringValue(cJSON_GetObjectItem(item, "channel"));
        const char *chat_id = cJSON_GetStringValue(cJSON_GetObjectItem(item, "chat_id"));

        if (!id || !name || !kind_str || !message) continue;

        strncpy(job->id, id, sizeof(job->id) - 1);
        strncpy(job->name, name, sizeof(job->name) - 1);
        strncpy(job->message, message, sizeof(job->message) - 1);
        strncpy(job->channel, channel ? channel : MIMI_CHAN_SYSTEM,
                sizeof(job->channel) - 1);
        strncpy(job->chat_id, chat_id ? chat_id : "cron",
                sizeof(job->chat_id) - 1);

        cJSON *enabled_j = cJSON_GetObjectItem(item, "enabled");
        job->enabled = enabled_j ? cJSON_IsTrue(enabled_j) : true;

        cJSON *delete_j = cJSON_GetObjectItem(item, "delete_after_run");
        job->delete_after_run = delete_j ? cJSON_IsTrue(delete_j) : false;

        if (strcmp(kind_str, "every") == 0) {
            job->kind = CRON_KIND_EVERY;
            cJSON *interval = cJSON_GetObjectItem(item, "interval_s");
            job->interval_s = (interval && cJSON_IsNumber(interval))
                              ? (uint32_t)interval->valuedouble : 0;
        } else if (strcmp(kind_str, "at") == 0) {
            job->kind = CRON_KIND_AT;
            cJSON *at_epoch = cJSON_GetObjectItem(item, "at_epoch");
            job->at_epoch = (at_epoch && cJSON_IsNumber(at_epoch))
                            ? (int64_t)at_epoch->valuedouble : 0;
        } else {
            continue; /* Unknown kind, skip */
        }

        cJSON *last_run = cJSON_GetObjectItem(item, "last_run");
        job->last_run = (last_run && cJSON_IsNumber(last_run))
                        ? (int64_t)last_run->valuedouble : 0;

        cJSON *next_run = cJSON_GetObjectItem(item, "next_run");
        job->next_run = (next_run && cJSON_IsNumber(next_run))
                        ? (int64_t)next_run->valuedouble : 0;

        s_job_count++;
    }

    cJSON_Delete(root);
    ESP_LOGI(TAG, "Loaded %d cron jobs", s_job_count);
    return ESP_OK;
}

static esp_err_t cron_save_jobs(void)
{
    cJSON *root = cJSON_CreateObject();
    cJSON *jobs_arr = cJSON_CreateArray();

    for (int i = 0; i < s_job_count; i++) {
        cron_job_t *job = &s_jobs[i];
        cJSON *item = cJSON_CreateObject();

        cJSON_AddStringToObject(item, "id", job->id);
        cJSON_AddStringToObject(item, "name", job->name);
        cJSON_AddBoolToObject(item, "enabled", job->enabled);
        cJSON_AddStringToObject(item, "kind",
            job->kind == CRON_KIND_EVERY ? "every" : "at");

        if (job->kind == CRON_KIND_EVERY) {
            cJSON_AddNumberToObject(item, "interval_s", job->interval_s);
        } else {
            cJSON_AddNumberToObject(item, "at_epoch", (double)job->at_epoch);
        }

        cJSON_AddStringToObject(item, "message", job->message);
        cJSON_AddStringToObject(item, "channel", job->channel);
        cJSON_AddStringToObject(item, "chat_id", job->chat_id);
        cJSON_AddNumberToObject(item, "last_run", (double)job->last_run);
        cJSON_AddNumberToObject(item, "next_run", (double)job->next_run);
        cJSON_AddBoolToObject(item, "delete_after_run", job->delete_after_run);

        cJSON_AddItemToArray(jobs_arr, item);
    }

    cJSON_AddItemToObject(root, "jobs", jobs_arr);

    char *json_str = cJSON_Print(root);
    cJSON_Delete(root);

    if (!json_str) {
        ESP_LOGE(TAG, "Failed to serialize cron jobs");
        return ESP_ERR_NO_MEM;
    }

    FILE *f = fopen(MIMI_CRON_FILE, "w");
    if (!f) {
        ESP_LOGE(TAG, "Failed to open %s for writing", MIMI_CRON_FILE);
        free(json_str);
        return ESP_FAIL;
    }

    size_t len = strlen(json_str);
    size_t written = fwrite(json_str, 1, len, f);
    fclose(f);
    free(json_str);

    if (written != len) {
        ESP_LOGE(TAG, "Cron save incomplete: %d/%d bytes", (int)written, (int)len);
        return ESP_FAIL;
    }

    ESP_LOGI(TAG, "Saved %d cron jobs to %s", s_job_count, MIMI_CRON_FILE);
    return ESP_OK;
}

/* ── Timer callback ───────────────────────────────────────────── */

static void cron_timer_callback(TimerHandle_t xTimer)
{
    (void)xTimer;

    time_t now = time(NULL);
    if (now < 1700000000) {
        /* System time not set yet (before ~2023), skip */
        return;
    }

    bool changed = false;

    for (int i = 0; i < s_job_count; i++) {
        cron_job_t *job = &s_jobs[i];
        if (!job->enabled) continue;
        if (job->next_run <= 0) continue;
        if (job->next_run > now) continue;

        /* Job is due — fire it */
        ESP_LOGI(TAG, "Cron job firing: %s (%s)", job->name, job->id);

        /* Push message to inbound queue */
        mimi_msg_t msg;
        memset(&msg, 0, sizeof(msg));
        strncpy(msg.channel, job->channel, sizeof(msg.channel) - 1);
        strncpy(msg.chat_id, job->chat_id, sizeof(msg.chat_id) - 1);
        msg.content = strdup(job->message);

        if (msg.content) {
            esp_err_t err = message_bus_push_inbound(&msg);
            if (err != ESP_OK) {
                ESP_LOGW(TAG, "Failed to push cron message: %s", esp_err_to_name(err));
                free(msg.content);
            }
        }

        /* Update state */
        job->last_run = now;

        if (job->kind == CRON_KIND_AT) {
            /* One-shot: disable or delete */
            if (job->delete_after_run) {
                /* Remove by shifting array */
                ESP_LOGI(TAG, "Deleting one-shot job: %s", job->name);
                for (int j = i; j < s_job_count - 1; j++) {
                    s_jobs[j] = s_jobs[j + 1];
                }
                s_job_count--;
                i--; /* Re-check this index */
            } else {
                job->enabled = false;
                job->next_run = 0;
            }
        } else {
            /* Recurring: compute next run */
            job->next_run = now + job->interval_s;
        }

        changed = true;
    }

    if (changed) {
        cron_save_jobs();
    }
}

/* ── Compute initial next_run for a new job ───────────────────── */

static void compute_initial_next_run(cron_job_t *job)
{
    time_t now = time(NULL);

    if (job->kind == CRON_KIND_EVERY) {
        job->next_run = now + job->interval_s;
    } else if (job->kind == CRON_KIND_AT) {
        if (job->at_epoch > now) {
            job->next_run = job->at_epoch;
        } else {
            /* Already in the past */
            job->next_run = 0;
            job->enabled = false;
        }
    }
}

/* ── Public API ───────────────────────────────────────────────── */

esp_err_t cron_service_init(void)
{
    return cron_load_jobs();
}

esp_err_t cron_service_start(void)
{
    if (s_cron_timer) {
        ESP_LOGW(TAG, "Cron timer already running");
        return ESP_OK;
    }

    /* Recompute next_run for all enabled jobs that don't have one */
    time_t now = time(NULL);
    for (int i = 0; i < s_job_count; i++) {
        cron_job_t *job = &s_jobs[i];
        if (job->enabled && job->next_run <= 0) {
            if (job->kind == CRON_KIND_EVERY) {
                job->next_run = now + job->interval_s;
            } else if (job->kind == CRON_KIND_AT && job->at_epoch > now) {
                job->next_run = job->at_epoch;
            }
        }
    }

    s_cron_timer = xTimerCreate(
        "cron",
        pdMS_TO_TICKS(MIMI_CRON_CHECK_INTERVAL_MS),
        pdTRUE,   /* auto-reload */
        NULL,
        cron_timer_callback
    );

    if (!s_cron_timer) {
        ESP_LOGE(TAG, "Failed to create cron timer");
        return ESP_FAIL;
    }

    if (xTimerStart(s_cron_timer, pdMS_TO_TICKS(1000)) != pdPASS) {
        ESP_LOGE(TAG, "Failed to start cron timer");
        return ESP_FAIL;
    }

    ESP_LOGI(TAG, "Cron service started (%d jobs, check every %ds)",
             s_job_count, MIMI_CRON_CHECK_INTERVAL_MS / 1000);
    return ESP_OK;
}

void cron_service_stop(void)
{
    if (s_cron_timer) {
        xTimerStop(s_cron_timer, pdMS_TO_TICKS(1000));
        xTimerDelete(s_cron_timer, pdMS_TO_TICKS(1000));
        s_cron_timer = NULL;
        ESP_LOGI(TAG, "Cron service stopped");
    }
}

esp_err_t cron_add_job(cron_job_t *job)
{
    if (s_job_count >= MAX_CRON_JOBS) {
        ESP_LOGW(TAG, "Max cron jobs reached (%d)", MAX_CRON_JOBS);
        return ESP_ERR_NO_MEM;
    }

    /* Generate ID */
    cron_generate_id(job->id);

    /* Set defaults for channel/chat_id if empty */
    if (job->channel[0] == '\0') {
        strncpy(job->channel, MIMI_CHAN_SYSTEM, sizeof(job->channel) - 1);
    }
    if (job->chat_id[0] == '\0') {
        strncpy(job->chat_id, "cron", sizeof(job->chat_id) - 1);
    }

    /* Compute initial next_run */
    job->enabled = true;
    job->last_run = 0;
    compute_initial_next_run(job);

    /* Copy into static array */
    s_jobs[s_job_count] = *job;
    s_job_count++;

    cron_save_jobs();

    ESP_LOGI(TAG, "Added cron job: %s (%s) kind=%s next_run=%lld",
             job->name, job->id,
             job->kind == CRON_KIND_EVERY ? "every" : "at",
             (long long)job->next_run);
    return ESP_OK;
}

esp_err_t cron_remove_job(const char *job_id)
{
    for (int i = 0; i < s_job_count; i++) {
        if (strcmp(s_jobs[i].id, job_id) == 0) {
            ESP_LOGI(TAG, "Removing cron job: %s (%s)", s_jobs[i].name, job_id);

            /* Shift remaining jobs down */
            for (int j = i; j < s_job_count - 1; j++) {
                s_jobs[j] = s_jobs[j + 1];
            }
            s_job_count--;

            cron_save_jobs();
            return ESP_OK;
        }
    }

    ESP_LOGW(TAG, "Cron job not found: %s", job_id);
    return ESP_ERR_NOT_FOUND;
}

void cron_list_jobs(const cron_job_t **jobs, int *count)
{
    *jobs = s_jobs;
    *count = s_job_count;
}