#include "app_base.h"
#include "imgui.h"

#include "gfx/shader_canvas.h"
#include "gfx/gl_shader.h"
#include "core/fps_overlay.h"
#include "seed_shaders.h"

#include <chrono>
#include <string>

static fn::gfx::ShaderCanvas g_canvas;
static std::string g_source = PLASMA;
static std::string g_last_err;
static int g_last_err_line = -1;
static std::chrono::steady_clock::time_point g_last_edit;
static bool g_dirty = true;

static void try_compile() {
    auto r = fn::gfx::compile_fragment(g_source);
    if (r.ok) {
        fn::gfx::canvas_set_program(g_canvas, r.program);
        g_last_err.clear();
        g_last_err_line = -1;
    } else {
        g_last_err = r.err_msg;
        g_last_err_line = r.err_line;
    }
}

static void mark_dirty() {
    g_last_edit = std::chrono::steady_clock::now();
    g_dirty = true;
}

static void load_preset(const char* src) {
    g_source = src;
    mark_dirty();
}

static void render() {
    if (!g_canvas.initialized) fn::gfx::canvas_init(g_canvas);

    if (g_dirty) {
        auto now = std::chrono::steady_clock::now();
        auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - g_last_edit).count();
        if (elapsed > 250) {
            try_compile();
            g_dirty = false;
        }
    }

    ImGui::DockSpaceOverViewport(0, ImGui::GetMainViewport());

    // --- Code panel ---
    if (ImGui::Begin("Code")) {
        if (ImGui::Button("Plasma"))  { load_preset(PLASMA); }
        ImGui::SameLine();
        if (ImGui::Button("Circle"))  { load_preset(CIRCLE); }
        ImGui::SameLine();
        if (ImGui::Button("Checker")) { load_preset(CHECKER); }

        ImVec2 avail = ImGui::GetContentRegionAvail();
        float footer_height = g_last_err.empty() ? 0.0f : ImGui::GetTextLineHeightWithSpacing() + 8.0f;
        ImVec2 editor_size(avail.x, avail.y - footer_height);

        char buf[1 << 16];
        size_t copy_len = g_source.size() < sizeof(buf) - 1 ? g_source.size() : sizeof(buf) - 1;
        memcpy(buf, g_source.c_str(), copy_len);
        buf[copy_len] = '\0';

        ImGui::PushFont(nullptr); // use default monospace-ish font
        if (ImGui::InputTextMultiline("##code", buf, sizeof(buf), editor_size,
                                      ImGuiInputTextFlags_AllowTabInput)) {
            g_source = buf;
            mark_dirty();
        }
        ImGui::PopFont();

        if (!g_last_err.empty()) {
            ImGui::Separator();
            if (g_last_err_line > 0) {
                ImGui::TextColored(ImVec4(1, 0.4f, 0.4f, 1), "line %d: %s",
                                   g_last_err_line, g_last_err.c_str());
            } else {
                ImGui::TextColored(ImVec4(1, 0.4f, 0.4f, 1), "%s", g_last_err.c_str());
            }
        }
    }
    ImGui::End();

    // --- Canvas panel ---
    if (ImGui::Begin("Canvas")) {
        fn::gfx::canvas_render(g_canvas, static_cast<float>(ImGui::GetTime()));
    }
    ImGui::End();

    // --- Controls panel ---
    if (ImGui::Begin("Controls")) {
        ImGui::TextDisabled("Controls (fase 2)");
        ImGui::Spacing();
        fps_overlay();
    }
    ImGui::End();
}

int main() {
    fn::AppConfig cfg;
    cfg.title  = "shaders_lab";
    cfg.width  = 1400;
    cfg.height = 860;
    int rc = fn::run_app(cfg, render);
    fn::gfx::canvas_destroy(g_canvas);
    return rc;
}