#if OS == .WINDOWS {
    #load "windows.jai";
} else #if (OS == .LINUX) || (OS == .MACOS) {
    #load "unix.jai";
} else {
    #assert(false, "Unsupported OS.");
}

#import "Basic";
#import "String";
#import "Thread";

Drawings :: struct {
    CornerBR                :: "\x6A";
    CornerTR                :: "\x6B";
    CornerTL                :: "\x6C";
    CornerBL                :: "\x6D";
    Cross                   :: "\x6E";
    LineH                   :: "\x71";
    TeeL                    :: "\x74";
    TeeR                    :: "\x75";
    TeeB                    :: "\x76";
    TeeT                    :: "\x77";
    LineV                   :: "\x78";

    Blank                   :: "\x5F";
    Diamond                 :: "\x60";
    Checkerboard            :: "\x61";
    PlusMinus               :: "\x67";
    LessThanOrEqual         :: "\x79";
    GreaterThanOrEqual      :: "\x7A";
    Pi                      :: "\x7B";
    NotEqual                :: "\x7C";
    CenteredDot             :: "\x7E";
}

Commands :: struct {
    EnterAlternateBuffer    :: "\e[?1049h";
    EnterMainBuffer         :: "\e[?1049l";

    EnterDrawingMode        :: "\e(0";
    EnterNormalMode         :: "\e(B";
    ClearScreen             :: "\e[2J";
    ClearLine               :: "\e[2K";

    RefreshWindow           :: "\e[7t"; // TODO Not yet tested.

    SetUTF8                 :: "\e%G"; // TODO TEST ME PLEASE

    // Cursor Position
    SetCursorPosition       :: "\e[%;%H";

    // Cursor Visibility
    ShowCursor              :: "\e[?25h";
    HideCursor              :: "\e[?25l";
    StartBlinking           :: "\e[?25h]";
    StopBlinking            :: "\e[?25l]";
    SaveCursorPosition      :: "\e7";
    RestoreCursorPosition   :: "\e8";

    // Cursor Shape
    DefaultShape            :: "\e[0 q";
    BlinkingBlockShape      :: "\e[1 q";
    SteadyBlockShape        :: "\e[2 q";
    BlinkingUnderlineShape  :: "\e[3 q";
    SteadyUnderlineShape    :: "\e[4 q";
    BlinkingBarShape        :: "\e[5 q";
    SteadyBarShape          :: "\e[6 q";

    // Input Mode
    KeypadAppMode           :: "\e=";
    KeypadNumMode           :: "\e>";
    CursorAppMode           :: "\e[?1h";
    CursorNormalMode        :: "\e[?1l";

    // Query State
    QueryCursorPosition     :: "\e[6n"; // Emits the cursor position as: "ESC [ <r> ; <c> R" Where <r> = row and <c> = column.
    QueryDeviceAttributes   :: "\e[0c";
    QueryWindowSizeInChars  :: "\e[18t"; // Emits the window size as: "ESC [ 8 <r> ; <c> t" Where <r> = row and <c> = column. TODO Does not work on windows.
    
}

// TODO Maybe make the OS_* procedures as inline?!

initialized := false;


input_buffer_mutex: Mutex;
input_buffer: string;
input_counter: s64;
read_buffer: [4096] u8;

input_process_thread: Thread;

Key :: u8; // TODO To be improved.
Keys :: enum u8 {
    None    :: 0;
    Resize  :: 1; //410; // TODO Why?!
}

key_semaphore: Semaphore;
key_mutex: Mutex;
key_input := Keys.None;
key_resize := Keys.None;

// Notes
// So, the semaphore usage should indicate the items on the key_queue.
// If we don't want to use a queue, maybe we can use two Key items, one for user input, and another, with higher priority, for Resize.

dam :: (msg: string) {
    print(msg, to_standard_error = true);
}

process_input :: (thread: *Thread) -> s64 {
    char: u8;
    dam(">START signal_input\n");
    defer dam(">STOP signal_input\n");
    while(true) {
        if initialized == false return 0;
        if key_input != Keys.None {
            dam("waiting..");
            sleep_milliseconds(100); // We could increase this value as a push-back mechanism if we're just hitting it repeateadly.
            dam("!\n\r");
            continue;
        }
        dam("reading..");
        bytes_read := OS_read_input(*char, 1);
        dam("!\n\r");
        if bytes_read > 0 {
            lock(*key_mutex);
            defer unlock(*key_mutex);
            key_input = xx char;
            dam("signaling..");
            dam("!\n\r");
            signal(*key_semaphore);
        }
    }
    return 0;
}

process_resize :: (signal : s32) #c_call {
    new_context : Context;
	push_context new_context {
	    if signal != SIGWINCH return;
	    lock(*key_mutex);
	    defer unlock(*key_mutex);
        // TODO Only signal the key_semaphore if we don't already have a Resize on the queue.
        if key_resize != Key.None continue;
        key_resize = Keys.Resize;
        signal(*key_semaphore);
    }
}

get_key :: (wait_milliseconds: s32) -> Key {
    wait_for(*key_semaphore, wait_milliseconds);
    
    lock(*key_mutex);
    defer unlock(*key_mutex);
    
    if key_resize != Keys.None {
        defer key_resize = Keys.None;
        return xx key_resize;
    }

    defer key_input = Keys.None;
    return xx key_input;
}


start :: () {
    if initialized == true return;
dam("A");
    // write_strings(Commands.HideCursor, Commands.SaveCursorPosition, Commands.EnterAlternateBuffer, Commands.SetUTF8);
    OS_prepare_terminal();
dam("B");
    input_buffer = alloc_string(4096);
    init(*input_buffer_mutex, "input_buffer_mutex");
    assert(thread_init(*input_process_thread, process_input), "Failed to initialize thread.");
dam("C");
    init(*key_semaphore);
    init(*key_mutex, "key_mutex");
dam("D");
    initialized = true;
    thread_start(*input_process_thread);
dam("E");
}

stop :: () {
    if initialized == false return;
    initialized = false;

    thread_deinit(*input_process_thread);
    destroy(*key_semaphore);
    
    OS_reset_terminal();
    // write_strings(Commands.EnterMainBuffer, Commands.RestoreCursorPosition, Commands.ShowCursor);
}

get_str :: () -> string {
    lock(*input_buffer_mutex);
    defer unlock(*input_buffer_mutex);
    return input_buffer;
    // return tprint("%", to_string(input_buffer));
    // print("%", tprint("%", input_buffer));
    // return tprint("%", input_buffer);
}

flush_input :: () {
    // TODO
    lock(*input_buffer_mutex);
    defer unlock(*input_buffer_mutex);
    input_buffer.count = 0;
}

draw_box :: (x: int, y: int, width: int, height: int) {

    // TODO Check if using a String_Builder improves performance (measure it)!
    // TODO Validate input parameters against the terminal size.
    assert(x > 0 && y > 0 && width > 1 && height > 1, "Invalid arguments.");

    auto_release_temp();
    
    tmp_string: string;
    
    tmp_string = tprint(Commands.SetCursorPosition, y, x);
    write_strings(
        Commands.EnterDrawingMode,
        tmp_string,
        Drawings.CornerTL
        );

    for 1..width-2 {
        write_string(Drawings.LineH);
    }
    write_string(Drawings.CornerTR);

    for idx: y+1..y+height-2 {
        tmpL := tprint(Commands.SetCursorPosition, idx, x);
        tmpR := tprint(Commands.SetCursorPosition, idx, x+width-1);
        write_strings(
            tmpL,
            Drawings.LineV,
            tmpR,
            Drawings.LineV);
    }

    tmpBL := tprint(Commands.SetCursorPosition, y+height-1, x);
    write_strings(
        tmpBL,
        Drawings.CornerBL);
    for 1..width-2 {
        write_string(Drawings.LineH);
    }
    write_string(Drawings.CornerBR);
    
    write_string(Commands.EnterNormalMode);
}

// TODO Maybe rename to "clear()"
clear_terminal :: inline () {
    assert(initialized, "TUI is not ready.");
    write_string(Commands.ClearScreen);
}

// TODO Maybe rename to "get_size()"
get_terminal_size :: () -> rows: int, columns: int {
    assert(initialized, "TUI is not ready.");
    rows, columns := OS_get_terminal_size();
    return rows, columns;
}

set_cursor_position :: (row: int, column: int) {
    auto_release_temp();
    tmp_string := tprint(Commands.SetCursorPosition, row, column);
    write_string(tmp_string);
}

get_cursor_position :: () -> row: int, column: int {
    assert(initialized, "TUI is not ready."); // TODO Should I use this inside each and every procedure?

    auto_release_temp();
    
    write_string(Commands.QueryCursorPosition);

    input := talloc_string(64);
    input.count = OS_read_input(input.data, input.count); // TODO Does not check for read errors.

    // Expected message format: \e[<r>;<c>R
    // where <r> is the number of rows and <c> of columns.
    assert(
        input[0] == #char "\e" &&
        input[1] == #char "[" &&
        input[input.count-1] == #char "R",
        "Query cursor position returned invalid response.");

    advance(*input, 2);
    parts := split(input, ";");
    row := parse_int(*parts[0]);
    column := parse_int(*parts[1]);
    return row, column;
}

Input_Mode :: enum u8 {
    HUMAN;      // Shows cursor, echoes input, and expects an enter at the end of the line.
    MACHINE;    // Hides cursor, hides input, and reads right away once the first input is available.
}

// read_input :: (allocator: Allocator = temp, $mode: Input_Mode = .HUMAN) -> string {
    // #if mode == .HUMAN {
        // write_string(Commands.ShowCursor);
        // defer write_string(Commands.HideCursor);
        // 
        // OS_set_input_mode(.HUMAN);
        // defer OS_set_input_mode(.MACHINE);
    // }
// 
    // assert(allocator.proc != null, "Argument 'allocator.proc' has invalid null value.");
// 
    // #assert(mode != .MACHINE); // TODO Keep an eye if I try to use read_input for machine read. Eventually, remove mode from the procedure arguments.
    // 
    // builder: String_Builder();
    // builder.allocator = allocator;
    // init_string_builder(*builder);
    // 
    // while(1) {
        // buffer := get_current_buffer(*builder);
        // buffer_data := get_buffer_data(buffer);
        // buffer.count = OS_read_input(buffer_data, buffer.allocated); // TODO Does not check for read errors.
        // if buffer.count == 0 || buffer_data[buffer.count-1] == #char "\n" break;
        // assert(buffer.count == buffer.allocated); // TODO If newline wasn't detected, it's because the buffer got full.
        // expand(*builder);
    // }
    // return builder_to_string(*builder, allocator);
// }


#if OS == .WINDOWS {
    // Prototyping zone... keep clear!
}
else #if OS == .LINUX || OS == .MACOS {
    // Prototyping zone... keep clear!
}