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

#include "esp_log.h"
#include "freertos/FreeRTOS.h"
#include "freertos/queue.h"
#include "freertos/task.h"

#include "ambient_weather.h"
#include "app_config.h"
#include "backlight.h"
#include "display_rgb.h"
#include "ha_client.h"
#include "ha_data.h"
#include "i2c_bus.h"
#include "lvgl_port.h"
#include "touch_gt911.h"
#include "ui_manager.h"
#include "wifi_manager.h"

static const char *TAG = "main";

/*
 * 6144 was measured with the old cloud client, whose TLS handshake was the
 * deepest this task ever got. The HA path is plain HTTP and shallower, but
 * ha_data_t is ~600 bytes and the JSON bodies are on the stack, so the
 * headroom is kept. Re-check the high-water-mark log if more work lands here.
 */
#define HA_TASK_STACK 6144
#define HA_TASK_PRIO  3
#define HA_FIRST_DELAY_MS 3000

/* The forecast changes hourly at most and costs a service call, so it is
 * polled far less often than the sensors. */
#define FORECAST_EVERY_N_POLLS 30

/* Consecutive failed polls before the displayed reading is treated as stale. */
#define STALE_AFTER_POLLS 2

/* Depth 8: a burst of taps while the network is slow should queue rather than
 * be dropped, but a user cannot meaningfully get more than a few ahead. */
#define CMD_QUEUE_DEPTH 8

typedef struct {
    int     index;
    bool    on;
    int16_t brightness;
} light_cmd_t;

static QueueHandle_t cmd_queue;

/* The single copy of what is on screen. Only the HA task touches it. */
static ha_data_t ha_data;

/*
 * Runs on the LVGL task with the LVGL lock held, so it must not block.
 * Queueing hands the HTTP request to the HA task; a request from here would
 * freeze rendering for the duration and deadlock anything waiting on the lock.
 */
static void light_cmd_from_ui(int index, bool on, int16_t brightness)
{
    const light_cmd_t cmd = { .index = index, .on = on, .brightness = brightness };

    if (cmd_queue == NULL || xQueueSend(cmd_queue, &cmd, 0) != pdTRUE) {
        ESP_LOGW(TAG, "Light command queue full, dropping command for index %d", index);
    }
}

/*
 * Fall back to the Ambient Weather cloud API when HA is unreachable.
 *
 * Only fills the outdoor readings -- indoor, sun, lights and forecast have no
 * cloud equivalent and stay as they were. That is deliberate: a partial screen
 * of live outdoor data beats a blank one, and the status line says the panel
 * is running on the fallback.
 */
static bool fill_from_cloud(ha_data_t *data)
{
    weather_data_t w;
    if (weather_update(&w) != ESP_OK) {
        return false;
    }

    data->outdoor_temp_f   = (ha_value_t){ w.temp_f, w.has_temp };
    data->outdoor_humidity = (ha_value_t){ w.humidity, w.has_humidity };
    data->wind_mph         = (ha_value_t){ w.wind_mph, w.has_wind };

    return w.has_temp;
}

static void ha_task(void *arg)
{
    char line[96];

    /*
     * Age is tracked in ticks, not wall time: with no SNTP the system clock
     * starts at the epoch. (The clock shown on screen comes from HA, which is
     * why the panel can display the time without knowing it.) Tick
     * subtraction is also wrap-safe.
     */
    TickType_t last_success = 0;
    int consecutive_failures = 0;
    bool have_reading = false;
    bool stack_logged = false;
    uint32_t poll_count = 0;

    vTaskDelay(pdMS_TO_TICKS(HA_FIRST_DELAY_MS));

    /*
     * Zero on the first pass so the dashboard populates immediately after
     * boot. The wait below is what paces the loop, and it sits at the top --
     * so a full-interval timeout here would leave the panel showing dashes
     * for HA_UPDATE_INTERVAL_MS before the first poll ever ran. Measured on
     * hardware as a 63-second blank screen.
     */
    TickType_t wait_ticks = 0;

    while (1) {
        /*
         * Wait for a light command, or time out and poll. A command wakes the
         * task immediately so a tap feels instant instead of waiting out the
         * poll interval.
         */
        light_cmd_t cmd;
        const bool have_cmd = (cmd_queue != NULL) &&
            (xQueueReceive(cmd_queue, &cmd, wait_ticks) == pdTRUE);

        wait_ticks = pdMS_TO_TICKS(HA_UPDATE_INTERVAL_MS);

        if (!wifi_is_connected()) {
            ui_set_status("WiFi: reconnecting...");
            continue;
        }

        /*
         * Freeze rendering for the duration of the network work. The redraw
         * and the flush into the PSRAM framebuffer compete with the LCD's own
         * DMA out of that same PSRAM; letting them overlap is what produces
         * visible artefacts. The panel keeps scanning the last completed
         * frame, so the screen simply holds still.
         */
        lvgl_port_pause();

        if (have_cmd) {
            const esp_err_t cmd_err = ha_light_command(cmd.index, cmd.on, cmd.brightness);
            if (cmd_err != ESP_OK) {
                ESP_LOGW(TAG, "Light command failed: %s", esp_err_to_name(cmd_err));
            }
        }

        esp_err_t err = ha_fetch_state(&ha_data);

        /* The forecast is a second request, so only fetch it when the first
         * one proved HA is reachable. */
        if (err == ESP_OK &&
            (ha_data.forecast_count == 0 || (poll_count % FORECAST_EVERY_N_POLLS) == 0)) {
            if (ha_fetch_forecast(&ha_data) != ESP_OK) {
                ESP_LOGW(TAG, "Forecast fetch failed; keeping previous days");
            }
        }

        bool on_fallback = false;
        if (err != ESP_OK) {
            on_fallback = fill_from_cloud(&ha_data);
        }

        lvgl_port_resume();

        poll_count++;

        if (err == ESP_OK || on_fallback) {
            last_success = xTaskGetTickCount();
            consecutive_failures = 0;
            have_reading = true;

            ui_update(&ha_data);
            ui_set_stale(false);

            if (on_fallback) {
                ui_set_status("Home Assistant unreachable - cloud weather only");
            } else {
                wifi_get_status(line, sizeof(line));
                ui_set_status(line);
            }

            if (!stack_logged) {
                stack_logged = true;
                ESP_LOGI(TAG, "HA task stack headroom: %u bytes",
                         (unsigned)(uxTaskGetStackHighWaterMark(NULL) * sizeof(StackType_t)));
            }
        } else {
            consecutive_failures++;
            ESP_LOGW(TAG, "Update failed (%d consecutive)", consecutive_failures);

            if (have_reading && consecutive_failures >= STALE_AFTER_POLLS) {
                const uint32_t age_min =
                    ((xTaskGetTickCount() - last_success) * portTICK_PERIOD_MS) / 60000U;
                ui_set_stale(true);
                snprintf(line, sizeof(line), "No update for %lum", (unsigned long)age_min);
                ui_set_status(line);
            } else {
                ui_set_status("Update failed");
            }
        }
    }
}

void app_main(void)
{
    ESP_LOGI(TAG, "Thermostat HMI -- CrowPanel 7.0\" ESP32-S3 (800x480)");

    /*
     * WiFi comes up FIRST, before the RGB panel exists.
     *
     * The panel's bounce-buffer ISR reads the framebuffer out of PSRAM, and
     * PSRAM shares the cache with flash on the ESP32-S3. Bringing up NVS and
     * the WiFi PHY writes calibration data to flash, which disables the cache
     * and faults that ISR. Doing it here means every flash write is finished
     * before the panel starts scanning.
     */
    const esp_err_t wifi_err = wifi_init_sta();
    if (wifi_err != ESP_OK) {
        ESP_LOGE(TAG, "WiFi not up yet -- polling starts when it connects");
    }

    /* LVGL core must exist before the display and touch drivers register
     * themselves with it. */
    ESP_ERROR_CHECK(lvgl_port_init());

    /* Shared bus: STC8H1K28 board controller and GT911 both live on it. */
    ESP_ERROR_CHECK(i2c_bus_init());

    /* Must precede touch_init(): the STC8H1K28 holds the GT911 in reset
     * until its init sequence runs. */
    if (backlight_init() != ESP_OK) {
        ESP_LOGE(TAG, "STC8H1K28 init failed -- backlight and touch will not work");
    }
    i2c_bus_scan(TAG);

    ESP_ERROR_CHECK(display_init());

    if (touch_init() != ESP_OK) {
        /* A dead touch panel should not stop the display from working -- but
         * it does mean the light tiles are unusable. */
        ESP_LOGW(TAG, "Touch unavailable -- continuing without input");
    }

    ui_init();
    ESP_ERROR_CHECK(lvgl_port_start());

    /* First frame is rendered by now, so it is safe to light the panel. */
    vTaskDelay(pdMS_TO_TICKS(100));
    ESP_ERROR_CHECK(backlight_set(255));

    if (wifi_err == ESP_OK) {
        char status[96];
        wifi_get_status(status, sizeof(status));
        ui_set_status(status);
    } else if (wifi_err == ESP_FAIL || wifi_err == ESP_ERR_TIMEOUT) {
        /* The event handler keeps retrying in the background; the HA task
         * polls wifi_is_connected(), so start it anyway rather than
         * permanently disabling updates because boot raced a slow AP. */
        ui_set_status("WiFi: connecting...");
    } else {
        /* No SSID configured (or setup failed outright) -- nothing will ever
         * connect, so there is no point starting the task. */
        ui_set_status("WiFi: not configured");
        return;
    }

    if (ha_client_init() != ESP_OK) {
        ui_set_status("Home Assistant: not configured");
        return;
    }

    /* Optional: only used when HA cannot be reached. A missing cloud API key
     * is not fatal, it just means there is no fallback. */
    if (weather_init() != ESP_OK) {
        ESP_LOGW(TAG, "Ambient Weather fallback unavailable (no credentials)");
    }

    cmd_queue = xQueueCreate(CMD_QUEUE_DEPTH, sizeof(light_cmd_t));
    if (cmd_queue == NULL) {
        ESP_LOGE(TAG, "Could not create the light command queue");
        return;
    }
    ui_set_light_cb(light_cmd_from_ui);

    xTaskCreate(ha_task, "ha", HA_TASK_STACK, NULL, HA_TASK_PRIO, NULL);

    ESP_LOGI(TAG, "System ready");
}