#include <GL/gl3w.h>    // Initialize with gl3wInit()
#include <GLFW/glfw3.h>

#include <imgui.h>
#include <imgui_impl_glfw.h>
#include <imgui_impl_opengl3.h>

#include <ctype.h>          // toupper, isprint
#include <limits.h>         // INT_MIN, INT_MAX
#include <math.h>           // sqrtf, powf, cosf, sinf, floorf, ceilf
#include <stdio.h>          // vsnprintf, sscanf, printf
#include <stdlib.h>         // NULL, malloc, free, atoi
#include <stdint.h>         // intptr_t

#include <string>
using std::string;

#define IM_NEWLINE  "\n"
#define IM_MAX(_A,_B)       (((_A) >= (_B)) ? (_A) : (_B))


struct ExampleAppConsole
{
    char                  InputBuf[256];
    ImVector<char*>       Items;
    ImVector<const char*> Commands;
    ImVector<char*>       History;
    int                   HistoryPos;    // -1: new line, 0..History.Size-1 browsing history.
    ImGuiTextFilter       Filter;
    bool                  AutoScroll;
    bool                  ScrollToBottom;

    ExampleAppConsole()
    {
        ClearLog();
        memset(InputBuf, 0, sizeof(InputBuf));
        HistoryPos = -1;
        Commands.push_back("HELP");
        Commands.push_back("HISTORY");
        Commands.push_back("CLEAR");
        Commands.push_back("CLASSIFY");  // "classify" is only here to provide an example of "C"+[tab] completing to "CL" and displaying matches.
        AutoScroll = true;
        ScrollToBottom = true;
        AddLog("All I do know is that in six hours I could be suffering from acute existence failure.");
    }
    ~ExampleAppConsole()
    {
        ClearLog();
        for (int i = 0; i < History.Size; i++)
            free(History[i]);
    }

    // Portable helpers
    static int   Stricmp(const char* str1, const char* str2)         { int d; while ((d = toupper(*str2) - toupper(*str1)) == 0 && *str1) { str1++; str2++; } return d; }
    static int   Strnicmp(const char* str1, const char* str2, int n) { int d = 0; while (n > 0 && (d = toupper(*str2) - toupper(*str1)) == 0 && *str1) { str1++; str2++; n--; } return d; }
    static char* Strdup(const char *str)                             { size_t len = strlen(str) + 1; void* buf = malloc(len); IM_ASSERT(buf); return (char*)memcpy(buf, (const void*)str, len); }
    static void  Strtrim(char* str)                                  { char* str_end = str + strlen(str); while (str_end > str && str_end[-1] == ' ') str_end--; *str_end = 0; }

    void    ClearLog()
    {
        for (int i = 0; i < Items.Size; i++)
            free(Items[i]);
        Items.clear();
        ScrollToBottom = true;
    }

    void    AddLog(const char* fmt, ...) IM_FMTARGS(2)
    {
        // FIXME-OPT
        char buf[1024];
        va_list args;
        va_start(args, fmt);
        vsnprintf(buf, IM_ARRAYSIZE(buf), fmt, args);
        buf[IM_ARRAYSIZE(buf)-1] = 0;
        va_end(args);
        Items.push_back(Strdup(buf));
        if (AutoScroll)
            ScrollToBottom = true;
    }

    void Draw(const char* title, bool* p_open)
    {
        ImGui::SetNextWindowSize(ImVec2(720,720), ImGuiCond_FirstUseEver);
        if (!ImGui::Begin(title, p_open))
        {
            ImGui::End();
            return;
        }

        // As a specific feature guaranteed by the library, after calling Begin() the last Item represent the title bar. So e.g. IsItemHovered() will return true when hovering the title bar.
        // Here we create a context menu only available from the title bar.
        if (ImGui::BeginPopupContextItem())
        {
            if (ImGui::MenuItem("Close Console"))
                *p_open = false;
            ImGui::EndPopup();
        }

        ImGui::TextWrapped("N2O");

        // TODO: display items starting from the bottom

        if (ImGui::SmallButton("Add Dummy Text"))  { AddLog("%d some text", Items.Size); AddLog("some more text"); AddLog("display very important message here!"); } ImGui::SameLine();
        if (ImGui::SmallButton("Add Dummy Error")) { AddLog("[error] something went wrong"); } ImGui::SameLine();
        if (ImGui::SmallButton("Clear")) { ClearLog(); } ImGui::SameLine();
        bool copy_to_clipboard = ImGui::SmallButton("Copy"); ImGui::SameLine();
        if (ImGui::SmallButton("Scroll to bottom")) ScrollToBottom = true;
        //static float t = 0.0f; if (ImGui::GetTime() - t > 0.02f) { t = ImGui::GetTime(); AddLog("Spam %f", t); }

        ImGui::Separator();

        // Options menu
        if (ImGui::BeginPopup("Options"))
        {
            if (ImGui::Checkbox("Auto-scroll", &AutoScroll))
                if (AutoScroll)
                    ScrollToBottom = true;
            ImGui::EndPopup();
        }

        // Options, Filter
        if (ImGui::Button("Options"))
            ImGui::OpenPopup("Options");
        ImGui::SameLine();
        Filter.Draw("Filter (\"incl,-excl\") (\"error\")", 180);
        ImGui::Separator();

        const float footer_height_to_reserve = ImGui::GetStyle().ItemSpacing.y + ImGui::GetFrameHeightWithSpacing(); // 1 separator, 1 input text
        ImGui::BeginChild("ScrollingRegion", ImVec2(0, -footer_height_to_reserve), false, ImGuiWindowFlags_HorizontalScrollbar); // Leave room for 1 separator + 1 InputText
        if (ImGui::BeginPopupContextWindow())
        {
            if (ImGui::Selectable("Clear")) ClearLog();
            ImGui::EndPopup();
        }

        // Display every line as a separate entry so we can change their color or add custom widgets. If you only want raw text you can use ImGui::TextUnformatted(log.begin(), log.end());
        // NB- if you have thousands of entries this approach may be too inefficient and may require user-side clipping to only process visible items.
        // You can seek and display only the lines that are visible using the ImGuiListClipper helper, if your elements are evenly spaced and you have cheap random access to the elements.
        // To use the clipper we could replace the 'for (int i = 0; i < Items.Size; i++)' loop with:
        //     ImGuiListClipper clipper(Items.Size);
        //     while (clipper.Step())
        //         for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++)
        // However, note that you can not use this code as is if a filter is active because it breaks the 'cheap random-access' property. We would need random-access on the post-filtered list.
        // A typical application wanting coarse clipping and filtering may want to pre-compute an array of indices that passed the filtering test, recomputing this array when user changes the filter,
        // and appending newly elements as they are inserted. This is left as a task to the user until we can manage to improve this example code!
        // If your items are of variable size you may want to implement code similar to what ImGuiListClipper does. Or split your data into fixed height items to allow random-seeking into your list.
        ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(4,1)); // Tighten spacing
        if (copy_to_clipboard)
            ImGui::LogToClipboard();
        for (int i = 0; i < Items.Size; i++)
        {
            const char* item = Items[i];
            if (!Filter.PassFilter(item))
                continue;

            // Normally you would store more information in your item (e.g. make Items[] an array of structure, store color/type etc.)
            bool pop_color = false;
            if (strstr(item, "[error]"))            { ImGui::PushStyleColor(ImGuiCol_Text, ImVec4(1.0f, 0.4f, 0.4f, 1.0f)); pop_color = true; }
            else if (strncmp(item, "# ", 2) == 0)   { ImGui::PushStyleColor(ImGuiCol_Text, ImVec4(1.0f, 0.8f, 0.6f, 1.0f)); pop_color = true; }
            ImGui::TextUnformatted(item);
            if (pop_color)
                ImGui::PopStyleColor();
        }
        if (copy_to_clipboard)
            ImGui::LogFinish();
        if (ScrollToBottom)
            ImGui::SetScrollHereY(1.0f);
        ScrollToBottom = false;
        ImGui::PopStyleVar();
        ImGui::EndChild();
        ImGui::Separator();

        // Command-line
        bool reclaim_focus = true;
        if (ImGui::InputText("Input", InputBuf, IM_ARRAYSIZE(InputBuf), ImGuiInputTextFlags_EnterReturnsTrue|ImGuiInputTextFlags_CallbackCompletion|ImGuiInputTextFlags_CallbackHistory, &TextEditCallbackStub, (void*)this))
        {
            char* s = InputBuf;
            Strtrim(s);
            if (s[0])
                ExecCommand(s);
            strcpy(s, "");
            reclaim_focus = true;
        }

        // Auto-focus on window apparition
        ImGui::SetItemDefaultFocus();
        if (reclaim_focus)
            ImGui::SetKeyboardFocusHere(-1); // Auto focus previous widget

        ImGui::End();
    }

    void    ExecCommand(const char* command_line)
    {
        AddLog("# %s\n", command_line);

        // Insert into history. First find match and delete it so it can be pushed to the back. This isn't trying to be smart or optimal.
        HistoryPos = -1;
        for (int i = History.Size-1; i >= 0; i--)
            if (Stricmp(History[i], command_line) == 0)
            {
                free(History[i]);
                History.erase(History.begin() + i);
                break;
            }
        History.push_back(Strdup(command_line));

        // Process command
        if (Stricmp(command_line, "CLEAR") == 0)
        {
            ClearLog();
        }
        else if (Stricmp(command_line, "HELP") == 0)
        {
            AddLog("Commands:");
            for (int i = 0; i < Commands.Size; i++)
                AddLog("- %s", Commands[i]);
        }
        else if (Stricmp(command_line, "HISTORY") == 0)
        {
            int first = History.Size - 10;
            for (int i = first > 0 ? first : 0; i < History.Size; i++)
                AddLog("%3d: %s\n", i, History[i]);
        }
        else
        {
            AddLog("Unknown command: '%s'\n", command_line);
        }

        // On commad input, we scroll to bottom even if AutoScroll==false
        ScrollToBottom = true;
    }

    static int TextEditCallbackStub(ImGuiInputTextCallbackData* data) // In C++11 you are better off using lambdas for this sort of forwarding callbacks
    {
        ExampleAppConsole* console = (ExampleAppConsole*)data->UserData;
        return console->TextEditCallback(data);
    }

    int     TextEditCallback(ImGuiInputTextCallbackData* data)
    {
        //AddLog("cursor: %d, selection: %d-%d", data->CursorPos, data->SelectionStart, data->SelectionEnd);
        switch (data->EventFlag)
        {
        case ImGuiInputTextFlags_CallbackCompletion:
            {
                // Example of TEXT COMPLETION

                // Locate beginning of current word
                const char* word_end = data->Buf + data->CursorPos;
                const char* word_start = word_end;
                while (word_start > data->Buf)
                {
                    const char c = word_start[-1];
                    if (c == ' ' || c == '\t' || c == ',' || c == ';')
                        break;
                    word_start--;
                }

                // Build a list of candidates
                ImVector<const char*> candidates;
                for (int i = 0; i < Commands.Size; i++)
                    if (Strnicmp(Commands[i], word_start, (int)(word_end-word_start)) == 0)
                        candidates.push_back(Commands[i]);

                if (candidates.Size == 0)
                {
                    // No match
                    AddLog("No match for \"%.*s\"!\n", (int)(word_end-word_start), word_start);
                }
                else if (candidates.Size == 1)
                {
                    // Single match. Delete the beginning of the word and replace it entirely so we've got nice casing
                    data->DeleteChars((int)(word_start-data->Buf), (int)(word_end-word_start));
                    data->InsertChars(data->CursorPos, candidates[0]);
                    data->InsertChars(data->CursorPos, " ");
                }
                else
                {
                    // Multiple matches. Complete as much as we can, so inputing "C" will complete to "CL" and display "CLEAR" and "CLASSIFY"
                    int match_len = (int)(word_end - word_start);
                    for (;;)
                    {
                        int c = 0;
                        bool all_candidates_matches = true;
                        for (int i = 0; i < candidates.Size && all_candidates_matches; i++)
                            if (i == 0)
                                c = toupper(candidates[i][match_len]);
                            else if (c == 0 || c != toupper(candidates[i][match_len]))
                                all_candidates_matches = false;
                        if (!all_candidates_matches)
                            break;
                        match_len++;
                    }

                    if (match_len > 0)
                    {
                        data->DeleteChars((int)(word_start - data->Buf), (int)(word_end-word_start));
                        data->InsertChars(data->CursorPos, candidates[0], candidates[0] + match_len);
                    }

                    // List matches
                    AddLog("Possible matches:\n");
                    for (int i = 0; i < candidates.Size; i++)
                        AddLog("- %s\n", candidates[i]);
                }

                break;
            }
        case ImGuiInputTextFlags_CallbackHistory:
            {
                // Example of HISTORY
                const int prev_history_pos = HistoryPos;
                if (data->EventKey == ImGuiKey_UpArrow)
                {
                    if (HistoryPos == -1)
                        HistoryPos = History.Size - 1;
                    else if (HistoryPos > 0)
                        HistoryPos--;
                }
                else if (data->EventKey == ImGuiKey_DownArrow)
                {
                    if (HistoryPos != -1)
                        if (++HistoryPos >= History.Size)
                            HistoryPos = -1;
                }

                // A better implementation would preserve the data on the current input line along with cursor position.
                if (prev_history_pos != HistoryPos)
                {
                    const char* history_str = (HistoryPos >= 0) ? History[HistoryPos] : "";
                    data->DeleteChars(0, data->BufTextLen);
                    data->InsertChars(0, history_str);
                }
            }
        }
        return 0;
    }
};

ExampleAppConsole console;

void DoAddLog(string s)
{
  console.AddLog("%s", s.c_str());
}


void ShowConsole(bool* p_open)
{
    console.Draw("Console", p_open);
}

static void glfw_error_callback(int error, const char* description)
{
    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
}

int gui(int, char**)
{
    // Setup window
    glfwSetErrorCallback(glfw_error_callback);
    if (!glfwInit())
        return 1;

    // Decide GL+GLSL versions
#if __APPLE__
    // GL 3.2 + GLSL 150
    const char* glsl_version = "#version 150";
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // Required on Mac
#else
    // GL 3.0 + GLSL 130
    const char* glsl_version = "#version 130";
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
    //glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
    //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // 3.0+ only
#endif

    // Create window with graphics context
    GLFWwindow* window = glfwCreateWindow(720, 720, "n2o.im", NULL, NULL);
    if (window == NULL)
        return 1;
    glfwMakeContextCurrent(window);
    glfwSwapInterval(1); // Enable vsync

    // Initialize OpenGL loader
#if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
    bool err = gl3wInit() != 0;
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
    bool err = glewInit() != GLEW_OK;
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
    bool err = gladLoadGL() == 0;
#else
    bool err = false; // If you use IMGUI_IMPL_OPENGL_LOADER_CUSTOM, your loader is likely to requires some form of initialization.
#endif
    if (err)
    {
        fprintf(stderr, "Failed to initialize OpenGL loader!\n");
        return 1;
    }

    // Setup Dear ImGui context
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO(); (void)io;

    // Setup Dear ImGui style
    //ImGui::StyleColorsDark();
    ImGui::StyleColorsClassic();

    // Setup Platform/Renderer bindings
    ImGui_ImplGlfw_InitForOpenGL(window, true);
    ImGui_ImplOpenGL3_Init(glsl_version);

    // Load Fonts
    // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
    // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
    // - If the file cannot be loaded, the function will return NULL. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
    // - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
    // - Read 'misc/fonts/README.txt' for more instructions and details.
    // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
    ImFontConfig config;
    // config.SizePixels = 14;
    // io.Fonts->AddFontDefault(&config);
    //io.Fonts->AddFontFromFileTTF("vendor/imgui/misc/fonts/Roboto-Medium.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("vendor/imgui/misc/fonts/Cousine-Regular.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("vendor/imgui/misc/fonts/DroidSans.ttf", 16.0f);
    io.Fonts->AddFontFromFileTTF("vendor/imgui/misc/fonts/ProggyClean.ttf", 13.0f);
    //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
    //IM_ASSERT(font != NULL);

    io.FontGlobalScale = 1.0f;

    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 0.00f);

    // Main loop
    while (!glfwWindowShouldClose(window))
    {
        // Poll and handle events (inputs, window resize, etc.)
        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
        glfwWaitEvents();

        // Start the Dear ImGui frame
        ImGui_ImplOpenGL3_NewFrame();
        ImGui_ImplGlfw_NewFrame();
        ImGui::NewFrame();

        bool console = true;
        ShowConsole(&console);

        // Rendering
        ImGui::Render();
        int display_w, display_h;
        glfwMakeContextCurrent(window);
        glfwGetFramebufferSize(window, &display_w, &display_h);
        glViewport(0, 0, display_w, display_h);
        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
        glClear(GL_COLOR_BUFFER_BIT);
        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

        glfwMakeContextCurrent(window);
        glfwSwapBuffers(window);
    }

    // Cleanup
    ImGui_ImplOpenGL3_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImGui::DestroyContext();

    glfwDestroyWindow(window);
    glfwTerminate();

    return 0;
}