#include "ui_manager.h"

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

#include "app_config.h"
#include "control.h"
#include "encoder.h"
#include "esp_log.h"
#include "lvgl_port.h"
#include "relay.h"
#include "wifi_manager.h"
#include "zigbee_client.h"

static const char *TAG = "ui";

#define REFRESH_PERIOD_MS       250
#define FOCUS_TIMEOUT_MS        8000

#define DEG "\xC2\xB0"          /* UTF-8 degree sign */

/* Colours. Amber for an active heat call — it reads as "warm" without the
 * alarm connotation of red, which is reserved for faults. */
#define COL_BG          0x101014
#define COL_TEXT        0xF0F0F0
#define COL_DIM         0x808088
#define COL_HEAT        0xFF9500
#define COL_FAULT       0xFF453A
#define COL_ARC_BG      0x2C2C30
#define COL_ARC_FG      0x0A84FF

typedef enum {
    FOCUS_SETPOINT = 0,
    FOCUS_ROOM,
    FOCUS_MODE,
    FOCUS_COUNT,
} focus_t;

static lv_obj_t *s_arc;
static lv_obj_t *s_lbl_temp;
static lv_obj_t *s_lbl_setpoint;
static lv_obj_t *s_lbl_room;
static lv_obj_t *s_lbl_mode;
static lv_obj_t *s_lbl_status;
static lv_obj_t *s_lbl_heat;

static focus_t s_focus;
static uint32_t s_focus_idle_ms;

/* ------------------------------------------------------------- helpers -- */

static float c_to_display(float c)
{
#if APP_UNITS_FAHRENHEIT
    return c * 9.0f / 5.0f + 32.0f;
#else
    return c;
#endif
}

/*
 * One detent.
 *
 * In Fahrenheit this is 5/9 C, which is exactly 1F. The default setpoint of
 * 20.0C is exactly 68F, so stepping by 5/9 from there keeps every displayed
 * value a whole number of degrees rather than drifting onto 67.9.
 */
static float detent_step_c(void)
{
#if APP_UNITS_FAHRENHEIT
    return 5.0f / 9.0f;
#else
    return 0.5f;
#endif
}

static const char *unit_suffix(void)
{
#if APP_UNITS_FAHRENHEIT
    return DEG "F";
#else
    return DEG "C";
#endif
}

/*
 * PRD 8.2: lv_label_set_text() invalidates unconditionally, even when the text
 * is identical, forcing a full repaint. At full-refresh that is an entire
 * 480x480 frame redrawn to change nothing, four times a second.
 */
static void set_text_if_changed(lv_obj_t *label, const char *text)
{
    const char *current = lv_label_get_text(label);
    if (!current || strcmp(current, text) != 0) {
        lv_label_set_text(label, text);
    }
}

static void set_color_if_changed(lv_obj_t *obj, uint32_t hex)
{
    lv_color_t want = lv_color_hex(hex);
    lv_color_t have = lv_obj_get_style_text_color(obj, LV_PART_MAIN);
    if (lv_color_to_u32(want) != lv_color_to_u32(have)) {
        lv_obj_set_style_text_color(obj, want, 0);
    }
}

/* --------------------------------------------------------------- build -- */

static lv_obj_t *make_label(lv_obj_t *parent, const lv_font_t *font,
                            uint32_t color, lv_align_t align, int x, int y)
{
    lv_obj_t *l = lv_label_create(parent);
    lv_obj_set_style_text_font(l, font, 0);
    lv_obj_set_style_text_color(l, lv_color_hex(color), 0);
    lv_obj_set_style_text_align(l, LV_TEXT_ALIGN_CENTER, 0);
    lv_obj_align(l, align, x, y);
    lv_label_set_text(l, "");
    return l;
}

static void build_screen(void)
{
    lv_obj_t *scr = lv_screen_active();
    lv_obj_set_style_bg_color(scr, lv_color_hex(COL_BG), 0);
    lv_obj_set_style_bg_opa(scr, LV_OPA_COVER, 0);
    lv_obj_remove_flag(scr, LV_OBJ_FLAG_SCROLLABLE);

    /*
     * Setpoint arc, just inside the panel edge. Its gap sits at the bottom so
     * the scale reads left-to-right over the top, and the bottom of the circle
     * stays free for the status line.
     */
    s_arc = lv_arc_create(scr);
    lv_obj_set_size(s_arc, 440, 440);
    lv_obj_center(s_arc);
    lv_arc_set_rotation(s_arc, 135);
    lv_arc_set_bg_angles(s_arc, 0, 270);
    lv_arc_set_range(s_arc, 0, 100);
    lv_obj_remove_style(s_arc, NULL, LV_PART_KNOB);
    lv_obj_remove_flag(s_arc, LV_OBJ_FLAG_CLICKABLE);
    lv_obj_set_style_arc_width(s_arc, 14, LV_PART_MAIN);
    lv_obj_set_style_arc_width(s_arc, 14, LV_PART_INDICATOR);
    lv_obj_set_style_arc_color(s_arc, lv_color_hex(COL_ARC_BG), LV_PART_MAIN);
    lv_obj_set_style_arc_color(s_arc, lv_color_hex(COL_ARC_FG),
                               LV_PART_INDICATOR);

    /* Room and mode above centre. */
    s_lbl_room = make_label(scr, &lv_font_montserrat_28, COL_TEXT,
                            LV_ALIGN_CENTER, 0, -120);
    s_lbl_mode = make_label(scr, &lv_font_montserrat_16, COL_DIM,
                            LV_ALIGN_CENTER, 0, -88);

    /* The number that matters. */
    s_lbl_temp = make_label(scr, &lv_font_montserrat_48, COL_TEXT,
                            LV_ALIGN_CENTER, 0, -20);

    s_lbl_setpoint = make_label(scr, &lv_font_montserrat_28, COL_DIM,
                                LV_ALIGN_CENTER, 0, 40);

    /* Heat-call indicator. */
    s_lbl_heat = make_label(scr, &lv_font_montserrat_20, COL_DIM,
                            LV_ALIGN_CENTER, 0, 88);

    /*
     * Status and faults. Kept at y=+140 rather than nearer the rim: on a
     * circular panel the horizontal room at the bottom shrinks fast, and a
     * long fault string clipped by the bezel is worse than no fault string.
     */
    s_lbl_status = make_label(scr, &lv_font_montserrat_16, COL_DIM,
                              LV_ALIGN_CENTER, 0, 140);
    lv_obj_set_width(s_lbl_status, 300);
    lv_label_set_long_mode(s_lbl_status, LV_LABEL_LONG_WRAP);
    lv_obj_align(s_lbl_status, LV_ALIGN_CENTER, 0, 140);
}

/* ------------------------------------------------------------- refresh -- */

static void refresh_temperatures(const control_state_t *st)
{
    char buf[32];

    if (isnan(st->governing_temp_c)) {
        set_text_if_changed(s_lbl_temp, "--" DEG);
    } else {
        snprintf(buf, sizeof(buf), "%.0f" DEG, c_to_display(st->governing_temp_c));
        set_text_if_changed(s_lbl_temp, buf);
    }

    /*
     * Show the effective setpoint, not the requested one. When the fallback
     * ladder has clamped it, the screen must say what the thermostat is
     * actually doing — the fault text below explains why.
     */
    snprintf(buf, sizeof(buf), "Set %.0f%s",
             c_to_display(st->effective_setpoint_c), unit_suffix());
    set_text_if_changed(s_lbl_setpoint, buf);

    int pct = (int)((st->effective_setpoint_c - CONTROL_SETPOINT_MIN_C) * 100.0f /
                    (CONTROL_SETPOINT_MAX_C - CONTROL_SETPOINT_MIN_C));
    if (pct < 0) {
        pct = 0;
    } else if (pct > 100) {
        pct = 100;
    }
    if (lv_arc_get_value(s_arc) != pct) {
        lv_arc_set_value(s_arc, pct);
    }
}

static void refresh_room_and_mode(const control_state_t *st)
{
    const char *room = (st->governing_room >= 0)
                           ? zigbee_client_room_name(st->governing_room)
                           : "No sensor";
    set_text_if_changed(s_lbl_room, room);

    char buf[48];
    switch (s_focus) {
    case FOCUS_ROOM:
        snprintf(buf, sizeof(buf), "> SELECT ROOM <");
        break;
    case FOCUS_MODE:
        snprintf(buf, sizeof(buf), "> MODE: %s <", control_mode_str(st->mode));
        break;
    default:
        snprintf(buf, sizeof(buf), "%s", control_mode_str(st->mode));
        break;
    }
    set_text_if_changed(s_lbl_mode, buf);
    set_color_if_changed(s_lbl_mode,
                         (s_focus == FOCUS_SETPOINT) ? COL_DIM : COL_ARC_FG);
}

static void refresh_heat(void)
{
    relay_status_t rs;
    relay_status(&rs);

    char buf[48];

    if (rs.heat_on) {
        snprintf(buf, sizeof(buf), LV_SYMBOL_CHARGE " HEAT  %lu:%02lu",
                 (unsigned long)(rs.on_seconds / 60),
                 (unsigned long)(rs.on_seconds % 60));
        set_color_if_changed(s_lbl_heat, COL_HEAT);
    } else if (rs.heat_requested && rs.hold_off_seconds > 0) {
        /* Wanted but rate-limited. Saying so beats looking broken. */
        snprintf(buf, sizeof(buf), "Waiting %lum",
                 (unsigned long)((rs.hold_off_seconds + 59) / 60));
        set_color_if_changed(s_lbl_heat, COL_DIM);
    } else {
        snprintf(buf, sizeof(buf), "Idle");
        set_color_if_changed(s_lbl_heat, COL_DIM);
    }

    set_text_if_changed(s_lbl_heat, buf);
}

static void refresh_status(const control_state_t *st)
{
    relay_status_t rs;
    relay_status(&rs);

    char buf[96];
    uint32_t color = COL_DIM;

    /*
     * Most severe first — one line, so it has to be the one that matters.
     *
     * The clock check has to come before the source check. A schedule with no
     * clock yet falls through to the coldest fresh room, which sets the source
     * to CONTROL_SRC_OTHER_ROOM; reporting that as "sensor stale" would send
     * you looking at a sensor when the actual problem is that SNTP has not
     * synced.
     */
    if (rs.fault != RELAY_FAULT_NONE) {
        snprintf(buf, sizeof(buf), "FAULT: %s", relay_fault_str(rs.fault));
        color = COL_FAULT;

    } else if (st->mode == ROOM_MODE_SCHEDULE && !st->schedule_clock_valid) {
        snprintf(buf, sizeof(buf), "No clock yet - using coldest room");
        color = COL_FAULT;

    } else if (st->source != CONTROL_SRC_SELECTED) {
        snprintf(buf, sizeof(buf), "%s", control_source_str(st->source));
        color = COL_FAULT;

    } else if (!wifi_manager_is_connected()) {
        snprintf(buf, sizeof(buf), LV_SYMBOL_WARNING " No WiFi");
        color = COL_FAULT;

    } else if (!zigbee_client_is_connected()) {
        snprintf(buf, sizeof(buf), LV_SYMBOL_WARNING " No broker");
        color = COL_FAULT;

    } else {
        int batt = zigbee_client_lowest_battery();
        if (batt >= 0 && batt < 20) {
            snprintf(buf, sizeof(buf), LV_SYMBOL_BATTERY_1 " Sensor battery %d%%",
                     batt);
            color = COL_FAULT;
        } else {
            snprintf(buf, sizeof(buf), "%u cycles/hr", rs.cycles_last_hour);
        }
    }

    set_text_if_changed(s_lbl_status, buf);
    set_color_if_changed(s_lbl_status, color);
}

/* --------------------------------------------------------------- input -- */

/*
 * PRD 8.2: LVGL does not bubble events to parents, so a handler on the screen
 * object never sees taps landing on a child widget. The encoder is not an
 * LVGL input device here at all — it is polled from this timer, which sidesteps
 * the whole question.
 */
static void handle_encoder(void)
{
    int delta = encoder_take_delta();
    encoder_button_event_t btn = encoder_take_button_event();

    if (delta != 0) {
        s_focus_idle_ms = 0;

        switch (s_focus) {
        case FOCUS_ROOM: {
            int n = zigbee_client_room_count();
            int room = control_get_selected_room() + delta;
            /* Wrap rather than clamp: with two rooms, clamping makes the knob
             * feel dead half the time. */
            room = ((room % n) + n) % n;
            control_select_room(room);
            break;
        }

        case FOCUS_MODE: {
            int mode = (int)control_get_mode() + delta;
            mode = ((mode % ROOM_MODE_COUNT) + ROOM_MODE_COUNT) % ROOM_MODE_COUNT;
            control_set_mode((room_mode_t)mode);
            break;
        }

        case FOCUS_SETPOINT:
        default:
            control_adjust_setpoint(detent_step_c() * (float)delta);
            break;
        }
    }

    if (btn == ENCODER_BTN_CLICK) {
        s_focus = (focus_t)((s_focus + 1) % FOCUS_COUNT);
        s_focus_idle_ms = 0;
    } else if (btn == ENCODER_BTN_LONG_PRESS) {
        s_focus = FOCUS_SETPOINT;
        s_focus_idle_ms = 0;
    }

    /* Fall back to the setpoint so the knob's default meaning is always the
     * temperature, however the user left it. */
    if (s_focus != FOCUS_SETPOINT) {
        s_focus_idle_ms += REFRESH_PERIOD_MS;
        if (s_focus_idle_ms >= FOCUS_TIMEOUT_MS) {
            s_focus = FOCUS_SETPOINT;
            s_focus_idle_ms = 0;
        }
    }
}

/* ---------------------------------------------------------------- tick -- */

static void refresh_timer_cb(lv_timer_t *timer)
{
    (void)timer;

    handle_encoder();

    control_state_t st;
    control_get_state(&st);

    refresh_temperatures(&st);
    refresh_room_and_mode(&st);
    refresh_heat();
    refresh_status(&st);
}

/* ---------------------------------------------------------------- init -- */

esp_err_t ui_manager_init(void)
{
    if (!lvgl_port_lock(1000)) {
        ESP_LOGE(TAG, "could not take LVGL lock");
        return ESP_ERR_TIMEOUT;
    }

    build_screen();
    lv_timer_create(refresh_timer_cb, REFRESH_PERIOD_MS, NULL);

    lvgl_port_unlock();

    ESP_LOGI(TAG, "ready (%s)", unit_suffix());
    return ESP_OK;
}