// ui_core.cpp - Clay wrapper implementation
// CLAY_IMPLEMENTATION must be defined exactly once before including clay.h.
// In the unity build, ui_core.h (which includes clay.h) has #pragma once,
// so we include clay.h directly here first to get the implementation compiled.

#include <stdlib.h>

#define CLAY_IMPLEMENTATION
#include "clay.h"

#include "ui/ui_core.h"

////////////////////////////////
// Theme global

UI_Theme g_theme = {};

void ui_init_theme() {
    g_theme.bg_dark       = Clay_Color{ 30,  30,  33, 255};
    g_theme.bg_medium     = Clay_Color{ 41,  41,  43, 255};
    g_theme.bg_light      = Clay_Color{ 51,  51,  56, 255};
    g_theme.bg_lighter    = Clay_Color{ 56,  56,  61, 255};
    g_theme.border        = Clay_Color{ 56,  56,  61, 255};
    g_theme.text          = Clay_Color{224, 224, 224, 255};
    g_theme.text_dim      = Clay_Color{112, 112, 112, 255};
    g_theme.accent        = Clay_Color{ 87, 138, 176, 255};
    g_theme.accent_hover  = Clay_Color{102, 153, 191, 255};
    g_theme.title_bar     = Clay_Color{ 26,  26,  28, 255};
    g_theme.scrollbar_bg  = Clay_Color{ 26,  26,  28, 255};
    g_theme.scrollbar_grab= Clay_Color{ 61,  61,  66, 255};
}

////////////////////////////////
// Clay error handler

static void clay_error_handler(Clay_ErrorData error) {
    char buf[512];
    int len = error.errorText.length < 511 ? error.errorText.length : 511;
    memcpy(buf, error.errorText.chars, len);
    buf[len] = '\0';
    fprintf(stderr, "[Clay Error] %s\n", buf);
}

////////////////////////////////
// Clay text measurement bridge
// Clay calls this; we forward to the app's UI_MeasureTextFn

static UI_Context *g_measure_ctx = nullptr;

static Clay_Dimensions clay_measure_text(Clay_StringSlice text, Clay_TextElementConfig *config, void *user_data) {
    UI_Context *ctx = (UI_Context *)user_data;
    if (!ctx || !ctx->measure_text_fn || text.length == 0) {
        return Clay_Dimensions{0, (float)config->fontSize};
    }
    Vec2F32 result = ctx->measure_text_fn(text.chars, text.length, (F32)config->fontSize, ctx->measure_text_user_data);
    return Clay_Dimensions{result.x, result.y};
}

////////////////////////////////
// Lifecycle

UI_Context *ui_create(F32 viewport_w, F32 viewport_h) {
    UI_Context *ctx = (UI_Context *)calloc(1, sizeof(UI_Context));

    uint32_t min_memory = Clay_MinMemorySize();
    ctx->clay_memory = malloc(min_memory);
    Clay_Arena clay_arena = Clay_CreateArenaWithCapacityAndMemory(min_memory, ctx->clay_memory);

    Clay_ErrorHandler err_handler = {};
    err_handler.errorHandlerFunction = clay_error_handler;
    err_handler.userData = ctx;

    ctx->clay_ctx = Clay_Initialize(clay_arena,
        Clay_Dimensions{viewport_w, viewport_h},
        err_handler);

    Clay_SetMeasureTextFunction(clay_measure_text, ctx);

    return ctx;
}

void ui_destroy(UI_Context *ctx) {
    if (!ctx) return;
    free(ctx->clay_memory);
    free(ctx);
}

void ui_begin_frame(UI_Context *ctx, F32 viewport_w, F32 viewport_h,
                    Vec2F32 mouse_pos, B32 mouse_down,
                    Vec2F32 scroll_delta, F32 dt)
{
    Clay_SetCurrentContext(ctx->clay_ctx);
    Clay_SetLayoutDimensions(Clay_Dimensions{viewport_w, viewport_h});
    Clay_SetPointerState(Clay_Vector2{mouse_pos.x, mouse_pos.y}, mouse_down != 0);
    Clay_UpdateScrollContainers(true, Clay_Vector2{scroll_delta.x, scroll_delta.y}, dt);
    Clay_BeginLayout();
}

Clay_RenderCommandArray ui_end_frame(UI_Context *ctx) {
    (void)ctx;
    return Clay_EndLayout();
}

void ui_set_measure_text_fn(UI_Context *ctx, UI_MeasureTextFn fn, void *user_data) {
    ctx->measure_text_fn = fn;
    ctx->measure_text_user_data = user_data;
}