// Cthulhu screen reader.
// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along with
// this program. If not, see <https://www.gnu.org/licenses/gpl-3.0.html>.

package review

import (
	"context"
	"errors"
	"time"

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

// ReadDocumentLine queues a caret-line capture and assembly request.
func (worker *Worker) ReadDocumentLine(focus atspi.ObjectID, offset int) (uint64, error) {
	if !focus.Valid() {
		return 0, ErrInvalidDirection
	}
	sequence := worker.lineSequence.Add(1)
	if sequence == 0 {
		sequence = worker.lineSequence.Add(1)
	}
	select {
	case worker.requests <- request{documentEpoch: worker.documentEpoch.Load(), line: true, lineRequest: sequence, lineFocus: focus, lineOffset: offset, queuedAt: time.Now()}:
		return sequence, nil
	default:
		return 0, ErrRequestQueueFull
	}
}

func (worker *Worker) readDocumentLine(ctx context.Context, tree *atspi.AccessibleTree, request uint64, focus atspi.ObjectID, offset int) (Result, *atspi.AccessibleTree) {
	result := Result{DocumentLine: true, DocumentLineRequest: request, DocumentLineFocus: focus}
	if !focus.Valid() {
		result.Err = ErrNoCurrent
		return result, tree
	}
	if tree != nil {
		if reference, err := tree.Reference(focus); err == nil {
			if line, err := tree.DocumentLineAtOffset(ctx, reference, offset); err == nil {
				result.DocumentLineData = line
				result.Moved = true
				return result, tree
			}
		}
	}
	captureContext, cancel := context.WithTimeout(ctx, worker.captureTimeout)
	captureStarted := time.Now()
	tree, err := worker.capturer.CaptureDocumentText(captureContext, focus)
	result.CaptureDuration = time.Since(captureStarted)
	cancel()
	if err != nil {
		result.Err = err
		return result, tree
	}
	if tree == nil {
		result.Err = errors.New("capture document text tree: nil tree")
		return result, nil
	}
	reference, err := tree.Reference(focus)
	if err != nil {
		result.Err = err
		return result, tree
	}
	line, err := tree.DocumentLineAtOffset(ctx, reference, offset)
	if err != nil {
		result.Err = err
		return result, tree
	}
	result.DocumentLineData = line
	result.Moved = true
	return result, tree
}