// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

// Package ocrcapture is used only by the short-lived, headless native helper.
// The reader's worker uses ocr.Capturer and never calls GTK/X11 capture in-process.
package ocrcapture

/*
#cgo pkg-config: gtk+-3.0 x11
#include "native.h"
*/
import "C"

import (
	"bytes"
	"context"
	"image"
	"image/png"
	"io"
	"os"
	"runtime"
	"unsafe"

	"git.stormux.org/storm/cthulhu/internal/ocr"
)

func Run(ctx context.Context, input io.Reader, output io.Writer) error {
	request, err := ocr.ReadCaptureRequest(input)
	if err != nil {
		return err
	}
	if err := ctx.Err(); err != nil {
		return err
	}
	header := ocr.CaptureHeader{Request: request, Status: "unavailable"}
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()
	// This backend captures physical X11 pixels, including Xwayland when it
	// provides them. Native display/source checks decide availability.
	_ = os.Setenv("GDK_BACKEND", "x11")
	_ = os.Setenv("NO_AT_BRIDGE", "1")
	kind := map[ocr.SourceKind]int{ocr.ObjectSource: 1, ocr.WindowSource: 2, ocr.DesktopSource: 3, ocr.ClipboardSource: 4}[request.Kind]
	native := C.cthulhu_ocr_capture(C.int(kind), C.ulong(request.Foreground), C.ulong(request.Window),
		C.int(request.Bounds.Min.X), C.int(request.Bounds.Min.Y), C.int(request.Bounds.Max.X), C.int(request.Bounds.Max.Y))
	defer C.cthulhu_ocr_capture_free(&native)
	if err := ctx.Err(); err != nil {
		return err
	}
	if native.status != 0 {
		header.Status = map[int]string{1: "unavailable", 2: "source", 3: "changed", 4: "limit"}[int(native.status)]
		return ocr.WriteCaptureResponse(output, header, nil)
	}
	header.Status = ""
	var pixels image.Image
	if request.Kind == ocr.ClipboardSource {
		data := C.GoBytes(unsafe.Pointer(native.clipboard), native.clipboardLength)
		config, decodeErr := png.DecodeConfig(bytes.NewReader(data))
		if decodeErr != nil {
			header.Status = "source"
		} else if config.Width <= 0 || config.Height <= 0 || config.Height > ocr.MaxPixels || config.Width > ocr.MaxPixels/config.Height {
			header.Status = "limit"
		} else {
			pixels, decodeErr = png.Decode(bytes.NewReader(data))
			if decodeErr != nil {
				header.Status = "source"
			}
		}
	} else {
		header.SourceWindow = uint64(native.sourceWindow)
		header.RootBounds = image.Rect(0, 0, int(native.rootWidth), int(native.rootHeight))
		header.SourceBounds = image.Rect(int(native.sourceX), int(native.sourceY), int(native.sourceX)+int(native.sourceWidth), int(native.sourceY)+int(native.sourceHeight))
		header.ScreenBounds = image.Rect(int(native.x), int(native.y), int(native.x)+int(native.width), int(native.y)+int(native.height))
		width, height := int(native.width), int(native.height)
		stride := int(C.gdk_pixbuf_get_rowstride(native.pixels))
		data := C.GoBytes(unsafe.Pointer(C.gdk_pixbuf_get_pixels(native.pixels)), C.int((height-1)*stride+width*3))
		owned := image.NewRGBA(image.Rect(0, 0, width, height))
		for row := range height {
			for column := range width {
				source := row*stride + column*3
				target := row*owned.Stride + column*4
				copy(owned.Pix[target:target+3], data[source:source+3])
				owned.Pix[target+3] = 255
			}
		}
		pixels = owned
	}
	return ocr.WriteCaptureResponse(output, header, pixels)
}