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

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

// https://learn.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences
// https://learn.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences#designate-character-set
// https://github.com/MicrosoftDocs/Console-Docs/blob/main/docs/console-virtual-terminal-sequences.md

isTUIActive := false; // TODO Rename this variable.


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 rename to "setup()"
start :: () {
    OS_prepare_terminal();
    write_strings(Commands.HideCursor, Commands.SaveCursorPosition, Commands.EnterAlternateBuffer, Commands.SetUTF8);
    isTUIActive = true;
}

// TODO Maybe rename to "reset()"
stop :: () {
    isTUIActive = false;
    write_strings(Commands.EnterMainBuffer, Commands.RestoreCursorPosition, Commands.ShowCursor);
    OS_reset_terminal();
}

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 () {
    write_string(Commands.ClearScreen);
}

// TODO Maybe rename to "get_size()"
get_terminal_size :: () -> rows: int, columns: int {
    rows, columns := OS_get_terminal_size();
    return rows, columns;
}

// read_input: () -> string {
    // return OS_read_input();
// }

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(isTUIActive, "TUI is not active."); // TODO
    write_string(Commands.QueryCursorPosition); // Returned 
    input := read_input(false);
    // Result: \e[21;1R
    assert(
        input.data[0] == #char "\e" &&
        input.data[1] == #char "[" &&
        input.data[input.count-1] == #char "R",
        "Query cursor position returned invalid response.");

    input.data += 2;
    print(">%<\n", input);
    parts := split(input, ";");
    row := parse_int(*parts[0]);
    column := parse_int(*parts[1]);
    return row, column;
}

read_input :: (blocking: bool = true) -> string {
    return OS_read_input(blocking);
}

// read_input: () -> string;

#if OS == .WINDOWS {

    OS_read_input :: (blocking: bool) -> string {
        result: string = ---;

        MAX_BYTES_TO_READ :: 1024;
        temp : [MAX_BYTES_TO_READ] u8;
        bytes_read : s32;

        if ReadConsoleA(stdin, temp.data, xx temp.count, *bytes_read) {
            result.data  = alloc(bytes_read);
            result.count = bytes_read;
            memcpy(result.data, temp.data, bytes_read);
        }
        return result;
    };
}
else #if OS == .LINUX || OS == .MACOS {

    OS_read_input :: (blocking: bool) -> string {

        term : My_Termios;
        tcgetattr(STDIN_FILENO, *term);

        // Input modes.
        Input_Modes :: enum u32 {
            IGNBRK;         // Ignore break condition.
            BRKINT;         // Signal interrupt on break.
            IGNPAR;         // Ignore characters with parity errors.
            PARMRK;         // Mark parity and framing errors.
            INPCK;          // Enable input parity check.
            ISTRIP;         // Strip 8th bit off characters.
            INLCR;          // Map NL to CR on input.
            IGNCR;          // Ignore CR.
            ICRNL;          // Map CR to NL on input.
            IXON;           // Enable start/stop output control.
            IXOFF;          // Enable start/stop input control.
            IXANY;          // Any character will restart after stop.
            __NOT_USED__;   
            IMAXBEL;        // Ring bell when input queue is full.
            IUCLC;          // Translate upper case input to lower case.
        }
            
        // IGNBRK              :u32: (1 << 0);     // Ignore break condition.
        // BRKINT              :u32: (1 << 1);     // Signal interrupt on break.
        // IGNPAR              :u32: (1 << 2);     // Ignore characters with parity errors.
        // PARMRK              :u32: (1 << 3);     // Mark parity and framing errors.
        // INPCK               :u32: (1 << 4);     // Enable input parity check.
        // ISTRIP              :u32: (1 << 5);     // Strip 8th bit off characters.
        // INLCR               :u32: (1 << 6);     // Map NL to CR on input.
        // IGNCR               :u32: (1 << 7);     // Ignore CR.
        // ICRNL               :u32: (1 << 8);     // Map CR to NL on input.
        // IXON                :u32: (1 << 9);     // Enable start/stop output control.
        // IXOFF               :u32: (1 << 10);    // Enable start/stop input control.
        // IXANY               :u32: (1 << 11);    // Any character will restart after stop.
        // IMAXBEL             :u32: (1 << 13);    // Ring bell when input queue is full.
        // IUCLC               :u32: (1 << 14);    // Translate upper case input to lower case.

        // IGNBRK              :u32: 0x0001;
        // BRKINT              :u32: 0x0002;
        // IGNCR               :u32: 0x0040;
        
        ECHO                :u32: 0x0004;
        ECHONL              :u32: 0x0010;
        ICANON              :u32: 0x0080;
        IEXTEN              :u32: 0x0400;

        backup: My_Termios;
        tcgetattr(STDIN_FILENO, *backup);

        if blocking {
            term = __term;
            // iflags: Input_Modes = (.IGNBRK | .BRKINT | .PARMRK | .ISTRIP | .INLCR | .IGNCR | .ICRNL | .IXON);
            // term.c_iflag |= xx iflags;
            // term.c_lflag |= (ECHO | ECHONL | ICANON | IEXTEN);
        }
        else {
            iflags: Input_Modes = (.IGNBRK | .BRKINT | .PARMRK | .ISTRIP | .INLCR | .IGNCR | .ICRNL | .IXON);
            term.c_iflag &= xx ~(iflags);
            term.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
        }
        
        // term.c_iflag &= 0xFFFFFA14;// ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);
        // term.c_oflag &= 0xFFFFFFFE;// ~OPOST;
        // term.c_lflag &= 0xFFFF7FB4;// ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
        // term.c_cflag &= 0xFFFFFECF;// ~(CSIZE | PARENB);
        // term.c_cflag |= 0x00000030;

        tcsetattr(STDIN_FILENO, 0, *term);

        result: string = ---;
        buffer: [8192] u8;
        write_string(Commands.ShowCursor);
        bytes_read := read(STDIN_FILENO, buffer.data, buffer.count-1);
        write_string(Commands.HideCursor);

        // TODO WIP WIP WIP
        result = to_string(buffer.data, bytes_read); // TODO WIP WIP WIP This is still using the stack allocated buffer and WILL FAIL!

        tcsetattr(STDIN_FILENO, 0, *backup);
        
        return result;
    };
}