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

package app

import (
	"context"
	"errors"
	"os/exec"
	"strings"
	"time"
)

type ocrTextCopier interface {
	Copy(context.Context, string) error
}

// xclip becomes the X11 selection owner after its short-lived parent exits.
// It releases ownership when another application replaces the clipboard.
type xclipOCRCopier struct{}

func (xclipOCRCopier) Copy(ctx context.Context, value string) error {
	if value == "" {
		return errors.New("empty OCR selection")
	}
	ctx, cancel := context.WithTimeout(ctx, 2*time.Second)
	defer cancel()
	command := exec.CommandContext(ctx, "xclip", "-selection", "clipboard", "-in")
	command.Stdin = strings.NewReader(value)
	return command.Run()
}

type ocrCopyRequest struct {
	ctx        context.Context
	generation uint64
	text       string
	automatic  bool
}

func (session *ocrSession) copy_selection_locked() {
	if session.cursor == nil || session.selectionAnchor < 0 || session.selectionAnchor == session.cursor.Offset() {
		session.status_locked("No OCR text selected")
		return
	}
	start, end := min(session.selectionAnchor, session.cursor.Offset()), max(session.selectionAnchor, session.cursor.Offset())
	value, ok := session.cursor.Slice(start, end)
	if !ok || value == "" || session.copier == nil || session.copyRequests == nil {
		session.status_locked("OCR copy unavailable")
		return
	}
	request := ocrCopyRequest{ctx: session.job.ctx, generation: session.generation, text: value}
	select {
	case session.copyRequests <- request:
	default:
		// Keep the newest explicit copy request without blocking the input loop.
		select {
		case <-session.copyRequests:
		default:
		}
		session.copyRequests <- request
	}
}

func (session *ocrSession) copy(request ocrCopyRequest) {
	if request.ctx.Err() != nil {
		return
	}
	err := session.copier.Copy(request.ctx, request.text)
	session.mu.Lock()
	defer session.mu.Unlock()
	if request.ctx.Err() != nil || request.generation != session.generation || !session.current_locked(session.job) {
		return
	}
	// A successful optional copy must not cancel initial Say All or replace its
	// routable braille frame. Explicit copies retain their normal confirmation.
	if request.automatic && err == nil && session.job.autoReadAll {
		return
	}
	message := "OCR text copied to clipboard"
	if err != nil {
		message = "OCR copy unavailable"
		session.logger.Debug("OCR copy failed", "error", err)
	}
	session.status_locked(message)
}