const std = @import("std");
const expect = std.testing.expect;
const print = std.debug.print;
const getenv = std.posix.getenv;
const ioctl = std.c.ioctl;

const c = @cImport({
    @cDefine("_NO_CRT_STDIO_INLINE", "1");
    @cInclude("sys/ioctl.h");
    @cInclude("stdio.h");
});

const Winsize = struct {
    ws_row: c_ushort = 0,
    ws_col: c_ushort = 0,
    ws_xpixel: c_ushort = 0,
    ws_ypixel: c_ushort = 0,
};
const Point = struct {
    x: i32,
    y: i32,
    z: i32,
};
const Vec3 = struct {
    a: Point,
    b: Point,
    c: Point,
};

pub fn main() !void {
    var win = Winsize{};

    win = try getTermDimension();

    print("winsize.ws_row: {}\nws_line: {}\nws_xpixel: {} \nws_ypixel: {}\n", .{ win.ws_row, win.ws_col, win.ws_xpixel, win.ws_ypixel });
    try fillBuffer();
    try createFile();
    if (getenv("TERM")) |buf| {
        print("Buffer:{s}\n", .{buf});
        const slice = getNum(buf);
        _ = slice;
        //for (slice) |num| {
        //    print("extracted number:\n{d}\n", .{num});
        //}
    } else {
        print("Error getenv\n", .{});
    }
}

fn getTermDimension() !Winsize {
    var w = Winsize{};
    var ret: u16 = 0;
    const err = error{CUnknown};
    //print("stdout_fileno: {}\n", .{@TypeOf(std.c.STDOUT_FILENO)});
    ret = @intCast(ioctl(std.c.STDOUT_FILENO, c.TIOCGWINSZ, &w));
    if (ret > 0) {
        return err.CUnknown;
    }
    //print("winsize.ws_row: {}\nws_line: {}\nws_xpixel: {} \nws_ypixel: {}\n", .{ w.ws_row, w.ws_col, w.ws_xpixel, w.ws_ypixel });
    return w;
}

fn getNum(str1: []const u8) []u64 {
    //_ = str1;
    var pos: u64 = 0;
    var num = std.mem.zeroes([64]u64);
    var num_res = std.mem.zeroes([16]u64);
    var it: u64 = 0;
    for (str1, 0..) |elem, it2| {
        if (elem >= 48 and elem <= 57) { //is ascii number?
            num[pos] = @intCast(elem - 48);
            if (pos <= @bitSizeOf(@TypeOf(pos))) {
                pos += 1;
            } else {
                print("ERROR int u64 oveflow! pos {d} ,max {d}\n", .{ pos, @bitSizeOf(@TypeOf(pos)) });
            }
        }
        //Calculate int out of characters
        if ((elem < 48 or elem > 57) or it2 == (str1.len - 1)) {
            if (pos != 0) {
                for (0..pos) |i| {
                    if (i < pos - 1) {
                        num_res[it] = num_res[it] + num[i] * (std.math.pow(u64, 10, (pos - i - 1)));
                    } else {
                        num_res[it] = num_res[it] + num[i];
                    }
                }
                //print("numres:{}={}\n", .{ it, num_res[it] });
                pos = 0;
                it += 1;
            }
        }
    }
    return &num_res;
}
fn createFile() !void {
    const file = try std.fs.cwd().openFile("junk-file.txt", .{ .mode = std.fs.File.OpenMode.read_write });
    defer file.close();

    const bytes_written = try file.writeAll("hello world!");
    //_ = bytes_written;
    std.debug.print("files written:{any}, {any}", .{ bytes_written, @TypeOf(bytes_written) });

    var buffer: [100]u8 = undefined;
    try file.seekTo(0);
    const bytes_read = try file.readAll(&buffer);
    print("buffer: {s} check: {s}\n", .{ buffer[0..bytes_read], "hello world!" });
    if (std.mem.eql(u8, buffer[0 .. bytes_read - 1], "hello world!") == true) {
        print("equal\n", .{});
    } else {
        print("not equal\n", .{});
    }
}
fn fillBuffer() !void {
    const allocator = std.heap.page_allocator;

    var w = Winsize{};
    var i: u64 = 0;
    w = try getTermDimension();
    const file = try std.fs.cwd().createFile("buffer.out", .{});
    defer file.close();

    var buffer = try allocator.alloc(u8, w.ws_row * w.ws_col * 4); //utf-8 can be 4 bytes long
    defer allocator.free(buffer);

    buffer[0] = 0;
    while (i < buffer.len) : (i += 4) {
        const slice = buffer[i .. i + 4];
        _ = try std.unicode.utf8Encode('\u{2588}', slice);
    }
    try pixel(buffer, w, 5, 10, '\u{1F702}');
    const vec = Vec3{
        .a = Point{ .x = 0, .y = 1, .z = 2 },
        .b = Point{ .x = 0, .y = 1, .z = 20 },
        .c = Point{ .x = 0, .y = 1, .z = 2 },
    };
    _ = vec;
    //triangle(vec);
    _ = try bresenham(buffer, w, Point{ .x = 10, .y = 40, .z = 0 }, Point{ .x = 30, .y = 10, .z = 0 });
    try file.writeAll(buffer);
}
fn pixel(buffer: []u8, w: Winsize, x: i64, y: i64, symbol: u21) !void {
    const i: usize = @intCast(4 * (x + y * w.ws_col));
    if (i < buffer.len) {
        const slice = buffer[i .. i + 4];
        print("slice:{u}\n", .{slice});
        _ = try std.unicode.utf8Encode(symbol, slice);
        print("slice after:{u}\n", .{slice});
        print("cols{}\ni: {}\n", .{ w.ws_col, i });
    } else {
        print("Error illegal memory access\n", .{});
    }
}
fn bresenham(buf: []u8, w: Winsize, p1: Point, p2: Point) !void {
    const x1: i32 = p1.x;
    const y1: i32 = p1.y;
    var x: i32 = 0;
    var y: i32 = 0;
    const dx = (p2.x - p1.x);
    print("p2: {} - {},{}\n", .{ p2.y, p1.y, p2.y - p1.y });
    const dy: i64 = (p2.y - p1.y);
    //const slope = dx/dy;
    var er: i64 = 0;

    if (dy > 0 and dy <= dx) {
        x = x1;
        y = y1;
    }
    if (dy < 0 and @abs(dy) > dx) {
        print("octant2\n", .{});
        x = y1;
        y = x1;
    }

    while (x <= p2.x) : (x += 1) {
        print("[bresenham]x:{},y:{},er:{},dx:{},dy:{}\n", .{ x, y, er, dx, dy });
        _ = try pixel(buf, w, x, y, '.');
        er += dy;
        if (2 * er >= dx) {
            y += 1;
            er -= dx;
        }
    }
}

//fn triangle(vec: Vec3) void {

//}