// HD-2D engine demo: meadow diorama with a WASD-controlled sprite.
//
// Controls: WASD/arrows move, Q/E rotate camera, right-drag orbit, wheel zoom,
// R rain, O overcast, G fog, L lightning, [ / ] time of day -/+ 1 h,
// F1 toggle tuning panel, F5 hot-reload shaders, F12 screenshot, T game UI showcase, Esc quit.
//
// Captures run hidden: --screenshot implies a hidden, input-ignoring window
// rendering into an offscreen target (--show opts back into a visible window;
// input is still ignored):
//   hd2d_demo --screenshot out.png [--frames 120] [--move x,y] [--pos x,z] [--show]
//             [--sun azimuthDeg,elevationDeg] [--yaw deg] [--dist units] [--size WxH] [--ui]
//             [--set name=value ...]   e.g. --set godRays=4 --set dof=0
//             [--hour H] [--rain X] [--overcast X] [--fog X] [--lightning] [--pitch deg]
//             [--sprite-test]          billboard feature row (atlas, flip, turn, alpha, flash, frames)
//             [--ui-demo]              game UI showcase (also key T): dialogue, choices, toasts, menu, nameplate

#include "DemoScene.h"
#include "hd2d/DayCycle.h"
#include "hd2d/DebugUI.h"
#include "hd2d/Log.h"
#include "hd2d/Renderer.h"
#include "hd2d/Screenshot.h"
#include "hd2d/UI.h"
#include "hd2d/Window.h"

#include <GLFW/glfw3.h>
#include <imgui.h>

#include <algorithm>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <string>
#include <utility>
#include <vector>

#ifndef HD2D_ASSET_DIR
#define HD2D_ASSET_DIR "assets"
#endif

namespace {

struct Options {
    std::string screenshot;
    int frames = 120;
    glm::vec2 move{0.0f};
    bool hasPos = false, hasSun = false, hasYaw = false, ui = false, spriteTest = false, uiDemo = false, show = false;
    bool hasHour = false, hasPitch = false, lightning = false;
    std::vector<std::pair<std::string, float>> settings;  // --set name=value
    glm::vec2 pos{0.0f}, sun{0.0f};
    float yaw = 0.0f, pitch = 0.0f, dist = 0.0f, rain = 0.0f, overcast = 0.0f, fog = 0.0f, hour = 12.0f;
    int width = 1600, height = 900;
};

bool parsePair(const char* s, float& a, float& b, char sep = ',') {
    char fmt[16];
    std::snprintf(fmt, sizeof fmt, "%%f%c%%f", sep);
    return std::sscanf(s, fmt, &a, &b) == 2;
}

Options parseArgs(int argc, char** argv) {
    Options o;
    for (int i = 1; i < argc; ++i) {
        auto next = [&]() -> const char* { return i + 1 < argc ? argv[++i] : ""; };
        if (!std::strcmp(argv[i], "--screenshot")) o.screenshot = next();
        else if (!std::strcmp(argv[i], "--frames")) o.frames = std::max(1, std::atoi(next()));
        else if (!std::strcmp(argv[i], "--move")) parsePair(next(), o.move.x, o.move.y);
        else if (!std::strcmp(argv[i], "--pos")) o.hasPos = parsePair(next(), o.pos.x, o.pos.y);
        else if (!std::strcmp(argv[i], "--sun")) o.hasSun = parsePair(next(), o.sun.x, o.sun.y);
        else if (!std::strcmp(argv[i], "--yaw")) o.hasYaw = true, o.yaw = float(std::atof(next()));
        else if (!std::strcmp(argv[i], "--dist")) o.dist = float(std::atof(next()));
        else if (!std::strcmp(argv[i], "--ui")) o.ui = true;
        else if (!std::strcmp(argv[i], "--show")) o.show = true;
        else if (!std::strcmp(argv[i], "--sprite-test")) o.spriteTest = true;
        else if (!std::strcmp(argv[i], "--ui-demo")) o.uiDemo = true;
        else if (!std::strcmp(argv[i], "--rain")) o.rain = float(std::atof(next()));
        else if (!std::strcmp(argv[i], "--overcast")) o.overcast = float(std::atof(next()));
        else if (!std::strcmp(argv[i], "--fog")) o.fog = float(std::atof(next()));
        else if (!std::strcmp(argv[i], "--lightning")) o.lightning = true;
        else if (!std::strcmp(argv[i], "--hour")) o.hasHour = true, o.hour = float(std::atof(next()));
        else if (!std::strcmp(argv[i], "--pitch")) o.hasPitch = true, o.pitch = float(std::atof(next()));
        else if (!std::strcmp(argv[i], "--set")) {
            std::string kv = next();
            auto eq = kv.find('=');
            if (eq != std::string::npos) o.settings.emplace_back(kv.substr(0, eq), float(std::atof(kv.c_str() + eq + 1)));
        }
        else if (!std::strcmp(argv[i], "--size")) {
            float w, h;
            if (parsePair(next(), w, h, 'x')) o.width = int(w), o.height = int(h);
        } else std::fprintf(stderr, "unknown argument: %s\n", argv[i]);
    }
    return o;
}

// Overrides a renderer setting by name (bools take 0/1). Returns false if unknown.
bool applySetting(hd2d::RenderSettings& s, const std::string& name, float v) {
    struct Entry {
        const char* name;
        float* f;
        bool* b;
    } table[] = {
        {"volumetrics", nullptr, &s.volumetrics},  {"dof", nullptr, &s.dof},
        {"bloom", nullptr, &s.bloom},              {"reflections", nullptr, &s.reflections},
        {"fogDensity", &s.fogDensity, nullptr},    {"fogHeightFalloff", &s.fogHeightFalloff, nullptr},
        {"godRays", &s.godRayIntensity, nullptr},  {"shaftStrength", &s.shaftStrength, nullptr},
        {"shaftCoverage", &s.shaftCoverage, nullptr}, {"cookieStrength", &s.cookieStrength, nullptr},
        {"exposure", &s.exposure, nullptr},        {"bloomStrength", &s.bloomStrength, nullptr},
        {"tiltShift", &s.tiltShift, nullptr},      {"focusRange", &s.focusRange, nullptr},
        {"shaftScale", &s.shaftScale, nullptr},    {"occluderFade", nullptr, &s.occluderFade},
        {"ssao", nullptr, &s.ssao},                {"groundAO", nullptr, &s.groundOcclusion},
        {"ssaoRadius", &s.ssaoRadius, nullptr},    {"ssaoIntensity", &s.ssaoIntensity, nullptr},
    };
    for (Entry& e : table)
        if (name == e.name) {
            if (e.f) *e.f = v;
            else *e.b = v != 0.0f;
            return true;
        }
    return false;
}

std::string timestampedScreenshotPath() {
    std::time_t t = std::time(nullptr);
    char buf[64];
    std::strftime(buf, sizeof buf, "screenshots/hd2d_%Y%m%d_%H%M%S.png", std::localtime(&t));
    return buf;
}

// Game UI showcase (key T or --ui-demo): typewriter dialogue with a portrait
// and choices, toasts, a menu, a status panel, a title, a themed ImGui window
// and a nameplate above the player. The ImGui theme is restored on exit.
struct UiShowcase {
    bool active = false;
    hd2d::ui::DialogueBox dialogue;
    hd2d::ui::Toasts toasts;
    hd2d::Texture portrait;
    ImGuiStyle savedStyle;
    float volume = 0.7f;  // state for the themed "Options" window
    bool subtitles = true;
    int textSpeed = 1;
    char playerName[32] = "Traveller";

    void open() {
        if (!active) savedStyle = ImGui::GetStyle();
        hd2d::ui::applyTheme();
        active = true;
        glm::vec4 b = portrait.opaqueBounds();  // square crop of the sprite's head and shoulders
        float side = b.z - b.x;
        dialogue.start({{"Warden Elise",
                         "Ah, a new face! Welcome to the meadow, traveller \xE2\x80\x94 the tall grass to the east hides "
                         "all manner of curious creatures, and the caf\xC3\xA9 by the bridge sells the finest bait\xE2\x80\xA6 "
                         "Will you take a field guide with you?",
                         ImTextureID(portrait.id()), ImVec2(b.x, b.y), ImVec2(b.z, b.y + side)}},
                        {"Yes, gladly.", "Not today.", "Tell me more first."});
        toasts.push("Field guide updated", IM_COL32(230, 190, 90, 255), 9.0f);
        toasts.push("New area: Sunlit Meadow", IM_COL32(120, 200, 160, 255), 9.0f);
    }
    void close() {
        dialogue.close();
        toasts.clear();
        ImGui::GetStyle() = savedStyle;
        active = false;
    }
    // Enter/Space advance, Up/Down pick a choice; Enter reopens a closed dialogue.
    void input(hd2d::Window& w) {
        if (dialogue.isOpen()) {
            if (w.keyPressed(GLFW_KEY_UP) || w.keyPressed(GLFW_KEY_W)) dialogue.moveChoice(-1);
            if (w.keyPressed(GLFW_KEY_DOWN) || w.keyPressed(GLFW_KEY_S)) dialogue.moveChoice(1);
            if ((w.keyPressed(GLFW_KEY_ENTER) || w.keyPressed(GLFW_KEY_SPACE)) && dialogue.advance()) {
                static const char* answers[] = {"Received a field guide", "Maybe next time", "Ask again with T"};
                int c = dialogue.choice();
                if (c >= 0) toasts.push(answers[c]);
            }
        } else if (w.keyPressed(GLFW_KEY_ENTER)) {
            open();
        }
    }
    void draw(glm::vec2 viewport, const hd2d::Camera& cam, glm::vec3 playerPos, float dt) {
        namespace ui = hd2d::ui;
        const ImVec2 vp(viewport.x, viewport.y);
        const float s = ui::scaleFor(vp);
        ImDrawList* dl = ImGui::GetForegroundDrawList();
        dialogue.update(dt);
        toasts.update(dt);

        ui::titleText(dl, ImVec2(vp.x * 0.5f, vp.y * 0.25f), "Meadow Tales", ui::kTitleSize * s);
        ui::menu(dl, ImVec2(vp.x * 0.13f, vp.y * 0.42f), {"Items", "Party", "Field Guide", "Settings", "Quit"}, 2,
                 "Menu", s);

        // Status panel with progress bars (top right).
        ImVec2 p0(vp.x - 380.0f * s - 40.0f * s, 40.0f * s), p1(vp.x - 40.0f * s, 40.0f * s + 150.0f * s);
        ui::panel(dl, p0, p1);
        ui::text(dl, ui::fonts().name, ui::kNameSize * s, ImVec2(p0.x + 28.0f * s, p0.y + 20.0f * s), ui::kGold,
                 "Traveller");
        ui::text(dl, ui::fonts().small, ui::kSmallSize * s, ImVec2(p1.x - 110.0f * s, p0.y + 22.0f * s),
                 ui::kTextMuted, "Lv. 12");
        const char* labels[] = {"HP", "SP"};
        const ImU32 colors[] = {IM_COL32(110, 190, 90, 255), IM_COL32(80, 150, 230, 255)};
        const float values[] = {0.82f, 0.45f};
        for (int i = 0; i < 2; ++i) {
            float y = p0.y + (68.0f + 38.0f * float(i)) * s;
            ui::text(dl, ui::fonts().small, ui::kSmallSize * s, ImVec2(p0.x + 28.0f * s, y - 4.0f * s), ui::kTextColor,
                     labels[i]);
            ui::progressBar(dl, ImVec2(p0.x + 80.0f * s, y + 2.0f * s), ImVec2(p1.x - 28.0f * s, y + 16.0f * s),
                            values[i], colors[i]);
        }

        glm::vec2 head;
        if (cam.worldToScreen(playerPos + glm::vec3(0.0f, 1.45f, 0.0f), viewport, head))
            ui::nameplate(dl, ImVec2(head.x, head.y), "Traveller", ui::kGold, s);

        // Standard widgets with applyTheme() and the game's small font.
        ImGui::PushFont(ui::fonts().small);
        ImGui::SetNextWindowPos(ImVec2(vp.x - 40.0f * s, vp.y * 0.36f), ImGuiCond_Always, ImVec2(1.0f, 0.0f));
        ImGui::Begin("Options", nullptr, ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings);
        ImGui::PushItemWidth(200.0f * s);
        ImGui::SliderFloat("Volume", &volume, 0.0f, 1.0f);
        ImGui::Checkbox("Subtitles", &subtitles);
        ImGui::Combo("Text speed", &textSpeed, "Slow\0Normal\0Fast\0");
        ImGui::InputText("Name", playerName, sizeof playerName);
        ImGui::Button("Apply");
        ImGui::PopItemWidth();
        ImGui::End();
        ImGui::PopFont();

        dialogue.draw(vp);
        toasts.draw(vp);
    }
};

// Owns every GL object so they are destroyed while the context still exists.
int run(hd2d::Window& window, const Options& opt) {
    const bool capture = !opt.screenshot.empty();

    hd2d::Renderer renderer;
    if (!renderer.init(std::string(HD2D_ASSET_DIR) + "/shaders", window.width(), window.height())) return 1;
    hd2d::OffscreenTarget offscreen;  // hidden captures render here instead of the backbuffer
    if (!window.visible()) {
        if (!offscreen.create(window.width(), window.height())) return 1;
        renderer.setOutputFramebuffer(offscreen.fbo());
    }
    for (const auto& [name, value] : opt.settings)
        if (!applySetting(renderer.settings, name, value)) HD2D_ERR("unknown setting '%s'", name.c_str());

    DemoScene demo;
    demo.spriteTest = opt.spriteTest;
    if (!demo.load(HD2D_ASSET_DIR)) {
        HD2D_ERR("failed to load demo assets from %s", HD2D_ASSET_DIR);
        return 1;
    }
    if (opt.hasPos) demo.placePlayer(opt.pos);
    if (opt.hasSun) {
        demo.scene.sun.azimuth = glm::radians(opt.sun.x);
        demo.scene.sun.elevation = glm::radians(opt.sun.y);
    }
    // Weather targets; captures start already at them.
    demo.weather.setRain(opt.rain);
    demo.weather.setOvercast(opt.overcast);
    demo.weather.setFog(opt.fog);
    demo.weather.setLightning(opt.lightning);
    demo.weather.snap();
    // Time of day: off (the scene's own look) until --hour, [ / ] or the hour slider.
    hd2d::DayCycle dayCycle;
    bool useDayCycle = opt.hasHour;
    float hour = opt.hasHour ? opt.hour : 12.0f;

    hd2d::DebugUI ui;
    if (!ui.init(window)) return 1;
    bool showUI = capture ? opt.ui : true;
    if (capture) ImGui::GetIO().ConfigFlags |= ImGuiConfigFlags_NoMouse | ImGuiConfigFlags_NoKeyboard;
    // Game UI fonts (ImGui's default font stays the default for the panels above).
    const auto viewportOf = [&] { return ImVec2(float(window.width()), float(window.height())); };
    hd2d::ui::loadFonts(std::string(HD2D_ASSET_DIR) + "/fonts", hd2d::ui::scaleFor(viewportOf()));
    UiShowcase showcase;
    showcase.portrait.load(std::string(HD2D_ASSET_DIR) + "/sprites/test_sprite.png", false, true);
    if (opt.uiDemo) showcase.open();

    hd2d::Camera cam;
    if (opt.hasYaw) cam.yaw = glm::radians(opt.yaw);
    if (opt.hasPitch) cam.pitch = glm::radians(opt.pitch);
    if (opt.dist > 0.0f) cam.distance = opt.dist;
    cam.target = demo.playerPos + glm::vec3(0, 0.7f, 0);

    using clock = std::chrono::steady_clock;
    auto last = clock::now();
    float time = 0.0f;
    int frame = 0;

    while (window.pollEvents()) {
        auto now = clock::now();
        float dt = std::min(std::chrono::duration<float>(now - last).count(), 0.05f);
        last = now;
        if (capture) dt = 1.0f / 60.0f;  // deterministic captures
        time += dt;

        if (window.resized()) {
            renderer.resize(window.width(), window.height());
            if (offscreen.fbo()) offscreen.resize(window.width(), window.height());
            hd2d::ui::loadFonts(std::string(HD2D_ASSET_DIR) + "/fonts", hd2d::ui::scaleFor(viewportOf()));
        }

        glm::vec2 move = opt.move;
        if (!capture && !ui.wantsKeyboard()) {  // captures ignore the user's input
            if (window.keyDown(GLFW_KEY_W) || window.keyDown(GLFW_KEY_UP)) move.y += 1.0f;
            if (window.keyDown(GLFW_KEY_S) || window.keyDown(GLFW_KEY_DOWN)) move.y -= 1.0f;
            if (window.keyDown(GLFW_KEY_D) || window.keyDown(GLFW_KEY_RIGHT)) move.x += 1.0f;
            if (window.keyDown(GLFW_KEY_A) || window.keyDown(GLFW_KEY_LEFT)) move.x -= 1.0f;
            if (window.keyDown(GLFW_KEY_Q)) cam.yaw -= dt * 1.2f;
            if (window.keyDown(GLFW_KEY_E)) cam.yaw += dt * 1.2f;
            if (window.keyPressed(GLFW_KEY_F1)) showUI = !showUI;
            if (window.keyPressed(GLFW_KEY_F5)) renderer.reloadShaders();
            if (window.keyPressed(GLFW_KEY_R)) demo.weather.setRain(demo.weather.targetRain() > 0.0f ? 0.0f : 1.0f);
            if (window.keyPressed(GLFW_KEY_O))
                demo.weather.setOvercast(demo.weather.targetOvercast() > 0.0f ? 0.0f : 1.0f);
            if (window.keyPressed(GLFW_KEY_G)) demo.weather.setFog(demo.weather.targetFog() > 0.0f ? 0.0f : 1.0f);
            if (window.keyPressed(GLFW_KEY_L)) demo.weather.setLightning(!demo.weather.lightning());
            if (window.keyPressed(GLFW_KEY_LEFT_BRACKET)) hour = std::fmod(hour + 23.0f, 24.0f), useDayCycle = true;
            if (window.keyPressed(GLFW_KEY_RIGHT_BRACKET)) hour = std::fmod(hour + 1.0f, 24.0f), useDayCycle = true;
            if (window.keyPressed(GLFW_KEY_ESCAPE)) window.requestClose();
            if (window.keyPressed(GLFW_KEY_T)) showcase.active ? showcase.close() : showcase.open();
            if (showcase.active) showcase.input(window);
            if (showcase.dialogue.isOpen()) move = opt.move;  // no walking while talking
        }
        if (!capture && !ui.wantsMouse()) {
            cam.distance = std::clamp(cam.distance * std::pow(0.9f, window.scrollDelta()), 8.0f, 45.0f);
            if (window.mouseDown(GLFW_MOUSE_BUTTON_RIGHT)) {
                glm::vec2 d = window.mouseDelta();
                cam.yaw += d.x * 0.005f;
                cam.pitch = std::clamp(cam.pitch + d.y * 0.004f, 0.2f, 1.35f);
            }
        }

        demo.update(dt, time, move, cam);
        glm::vec3 desired = demo.playerPos + glm::vec3(0, 0.7f, 0);
        cam.target += (desired - cam.target) * (capture ? 1.0f : std::min(1.0f, dt * 6.0f));

        if (useDayCycle) demo.weather.setClearLook(dayCycle.look(hour));
        demo.weather.update(dt, demo.scene, renderer.settings);
        renderer.render(demo.scene, cam, time);

        if (showUI || opt.spriteTest || showcase.active) {
            ui.beginFrame();
            if (showUI) {
                hd2d::DebugUI::renderSettingsPanel(renderer.settings, demo.scene, renderer.gpuFrameMs());
                const float prevHour = hour;
                hd2d::DebugUI::weatherPanel(demo.weather, &dayCycle, &hour);
                if (hour != prevHour) useDayCycle = true;
                ImGui::SetNextWindowPos(ImVec2(float(window.width()) - 12.0f, 12.0f), ImGuiCond_FirstUseEver,
                                        ImVec2(1.0f, 0.0f));
                ImGui::SetNextWindowBgAlpha(0.5f);
                ImGui::Begin("Controls", nullptr, ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoTitleBar);
                ImGui::TextUnformatted("WASD move | Q/E rotate | RMB orbit | wheel zoom");
                ImGui::TextUnformatted("R rain | O overcast | G fog | L lightning | [ ] hour -/+");
                ImGui::TextUnformatted("F1 panel | F5 reload shaders | F12 screenshot");
                ImGui::Text("player %.1f %.1f %.1f", demo.playerPos.x, demo.playerPos.y, demo.playerPos.z);
                ImGui::End();
            }
            // Sprite test captions, projected with Camera::worldToScreen.
            ImDrawList* dl = ImGui::GetForegroundDrawList();
            const glm::vec2 viewport(float(window.width()), float(window.height()));
            for (const DemoScene::Label& l : demo.labels) {
                glm::vec2 px;
                if (!cam.worldToScreen(l.pos, viewport, px)) continue;
                ImVec2 ts = ImGui::CalcTextSize(l.text);
                dl->AddText(ImVec2(px.x - ts.x * 0.5f, px.y - ts.y), IM_COL32(255, 255, 255, 255), l.text);
            }
            if (showcase.active) showcase.draw(viewport, cam, demo.playerPos, dt);
            ui.endFrame();
        }

        ++frame;
        if (!capture && window.keyPressed(GLFW_KEY_F12))
            hd2d::saveScreenshot(timestampedScreenshotPath(), window.width(), window.height());
        if (capture && frame >= opt.frames) {
            hd2d::saveScreenshot(opt.screenshot, window.width(), window.height(), renderer.outputFramebuffer());
            HD2D_LOG("player at %.2f %.2f %.2f, GPU %.2f ms", demo.playerPos.x, demo.playerPos.y, demo.playerPos.z,
                     renderer.gpuFrameMs());
            break;
        }
        window.swapBuffers();
    }
    ui.shutdown();
    return 0;
}

}  // namespace

int main(int argc, char** argv) {
    Options opt = parseArgs(argc, argv);
    hd2d::Window window;
    // Captures use a fixed-size (floating) window so screenshots are reproducible,
    // hidden unless --show so they never pop up or take the user's input.
    const bool capture = !opt.screenshot.empty();
    if (!window.create(opt.width, opt.height, "HD-2D Engine Demo", true, !capture, !capture || opt.show)) return 1;
    int rc = run(window, opt);
    window.destroy();
    return rc;
}