module sapp

import os
import stbi

#define SOKOL_VALIDATE_NON_FATAL 1

// v_sapp_gl_read_rgba_pixels reads pixles from the OpenGL buffer into `pixels`.
fn C.v_sapp_gl_read_rgba_pixels(x int, y int, width int, height int, pixels charptr)

// screenshot takes a screenshot of the current window and
// saves it to `path`. The format is inferred from the extension
// of the file name in `path`.
//
// Supported formats are: `.png`, `.ppm`.
pub fn screenshot(path string) ! {
    match os.file_ext(path) {
        '.png' {
            return screenshot_png(path)
        }
        '.ppm' {
            return screenshot_ppm(path)
        }
        else {
            return error(@MOD + '.' + @FN + ' currently only supports .png and .ppm files.')
        }
    }
}

// screenshot_ppm takes a screenshot of the current window and
// saves it to `path` as a .ppm file.
@[manualfree]
pub fn screenshot_ppm(path string) ! {
    ss := screenshot_window()
    write_rgba_to_ppm(path, ss.width, ss.height, 4, ss.pixels)!
    unsafe { ss.destroy() }
}

// screenshot_png takes a screenshot of the current window and
// saves it to `path` as a .png file.
@[manualfree]
pub fn screenshot_png(path string) ! {
    ss := screenshot_window()
    stbi.set_flip_vertically_on_write(true)
    stbi.stbi_write_png(path, ss.width, ss.height, 4, ss.pixels, ss.width * 4)!
    unsafe { ss.destroy() }
}

// write_rgba_to_ppm writes `pixels` data in RGBA format to PPM3 format.
fn write_rgba_to_ppm(path string, w int, h int, components int, pixels &u8) ! {
    mut f_out := os.create(path)!
    defer {
        f_out.close()
    }
    f_out.writeln('P3')!
    f_out.writeln('${w} ${h}')!
    f_out.writeln('255')!
    for i := h - 1; i >= 0; i-- {
        for j := 0; j < w; j++ {
            idx := i * w * components + j * components
            unsafe {
                r := int(pixels[idx])
                g := int(pixels[idx + 1])
                b := int(pixels[idx + 2])
                f_out.write_string('${r} ${g} ${b} ')!
            }
        }
    }
}