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

package review

import (
	"context"
	"errors"
	"strings"
	"unicode/utf8"

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

// Assemble from a private cursor: collecting speech must not move the user's
// browse position to the end before any of it has actually been spoken.
func (worker *Worker) readAll(ctx context.Context, cursor *DocumentCursor) Result {
	result := Result{DocumentFocus: worker.focus()}
	if !result.DocumentFocus.Valid() {
		result.Err = ErrNoCurrent
		return result
	}
	if cursor != nil {
		cursor = &DocumentCursor{tree: cursor.tree, active: cursor.active, places: append([]documentPlace(nil), cursor.places...)}
		_, result.Err = cursor.syncActionFocus(ctx, result.DocumentFocus)
	} else {
		result.Err = ErrNoCurrent
	}
	if documentNeedsCapture(result.Err) {
		cursor, result.Err = worker.refreshDocumentCursor(ctx, cursor, result.DocumentFocus)
	}
	if documentNeedsCapture(result.Err) {
		cursor, result.Err = worker.refreshDocumentCursor(ctx, cursor, result.DocumentFocus)
	}
	if errors.Is(result.Err, atspi.ErrNotInDocument) {
		if reader, ok := worker.nativeCapturerFor(result.DocumentFocus).(interface {
			ReadFocusedText(context.Context, atspi.ObjectID) (atspi.DocumentContent, error)
		}); ok {
			deadline, cancel := context.WithTimeout(ctx, worker.captureTimeout)
			defer cancel()
			var content atspi.DocumentContent
			content, result.Err = reader.ReadFocusedText(deadline, result.DocumentFocus)
			if result.Err == nil {
				result.ReadAllLines = focusedReadAllLines(content)
				epoch := worker.documentEpoch.Load()
				result.ReadAllProgress = func(index int) {
					if index < 0 || index >= len(result.ReadAllLines) || content.Text == "" {
						return
					}
					part := result.ReadAllLines[index].Contents[0]
					part.Snapshot.Text = part.Text
					position := DocumentPosition{Offset: part.Start, Snapshot: part.Snapshot}
					select {
					case worker.requests <- request{documentEpoch: epoch, readPosition: &position, readFocus: result.DocumentFocus}:
					default:
					}
				}
			}
		}
		return result
	}
	if result.Err != nil {
		return result
	}
	reader, ok := worker.nativeCapturerFor(result.DocumentFocus).(DocumentCaretReader)
	if !ok {
		result.Err = errors.New("read all: document text reader unavailable")
		return result
	}
	command := CaretReadLine
	var previous DocumentPosition
	var positions []DocumentPosition
	epoch := worker.documentEpoch.Load()
	result.ReadAllProgress = func(index int) {
		if index < 0 || index >= len(positions) {
			return
		}
		position := positions[index]
		select {
		case worker.requests <- request{documentEpoch: epoch, readPosition: &position, readTree: cursor.tree, readFocus: result.DocumentFocus}:
		default:
		}
	}
	bytes := 0
	var movement DocumentCaretMove
	var err error
	for {
		if err := ctx.Err(); err != nil {
			result.Err = err
			return result
		}
		movement, cursor, err = worker.readAllMove(ctx, cursor, reader, command, result.DocumentFocus)
		if err != nil {
			result.Err = err
			return result
		}
		if !movement.Moved {
			return result
		}
		if command == CaretNextLine && movement.Position.Object == previous.Object && movement.Position.Offset <= previous.Offset {
			result.Err = errors.New("read all: text provider did not advance")
			return result
		}
		previous = movement.Position
		movement.Position.Snapshot.Misspelled = movement.Misspelled
		line := atspi.DocumentLine{Document: movement.Position.Document, Contents: []atspi.DocumentContent{{Snapshot: movement.Position.Snapshot, Text: movement.Text, RawText: movement.RawText}}}
		owner, err := cursor.tree.DocumentContext(movement.Position.Object)
		if err != nil {
			if !documentNeedsCapture(err) {
				result.Err = err
				return result
			}
			refreshed, refreshErr := worker.refreshDocumentCursor(ctx, cursor, result.DocumentFocus)
			if refreshErr != nil {
				result.Err = refreshErr
				return result
			}
			cursor = refreshed
			owner = atspi.DocumentContext{}
		} else {
			line.Context = owner.Ancestors
			roles := map[string]bool{movement.Position.Snapshot.Role: true}
			for _, ancestor := range owner.Ancestors {
				if (ancestor.Role == "link" || ancestor.Role == "heading") && !roles[ancestor.Role] {
					roles[ancestor.Role] = true
					ancestor.Name = ""
					line.Contents = append(line.Contents, atspi.DocumentContent{Snapshot: ancestor})
				}
			}
		}
		bytes += len(movement.Text) + len(movement.Position.Snapshot.Name)
		if bytes > 1<<20 || len(result.ReadAllLines) >= 32768 {
			result.Err = errors.New("read all: document exceeds speech capture limit")
			return result
		}
		result.ReadAllLines = append(result.ReadAllLines, line)
		positions = append(positions, movement.Position)
		command = CaretNextLine
	}
}

func (worker *Worker) readAllMove(ctx context.Context, cursor *DocumentCursor, reader DocumentCaretReader, command DocumentCaretCommand, focus atspi.ObjectID) (DocumentCaretMove, *DocumentCursor, error) {
	deadline, cancel := context.WithTimeout(ctx, worker.captureTimeout)
	movement, err := cursor.MoveCaret(deadline, reader, command)
	cancel()
	if err == nil || !documentNeedsCapture(err) {
		return movement, cursor, err
	}
	cursor, refreshErr := worker.refreshDocumentCursor(ctx, cursor, focus)
	if refreshErr != nil {
		return movement, cursor, refreshErr
	}
	deadline, cancel = context.WithTimeout(ctx, worker.captureTimeout)
	defer cancel()
	movement, err = cursor.MoveCaret(deadline, reader, command)
	return movement, cursor, err
}

func (worker *Worker) followReadAll(ctx context.Context, cursor *DocumentCursor, request request) (*DocumentCursor, bool) {
	if !request.readPosition.Document.Valid() {
		if setter, ok := worker.nativeCapturerFor(request.readFocus).(interface {
			SetFocusedTextCaret(context.Context, atspi.ObjectID, int) error
		}); ok {
			deadline, cancel := context.WithTimeout(ctx, worker.captureTimeout)
			defer cancel()
			return cursor, setter.SetFocusedTextCaret(deadline, request.readFocus, request.readPosition.Offset) == nil
		}
		return cursor, false
	}
	if cursor == nil || cursor.tree != request.readTree {
		cursor, _ = NewDocumentCursor(request.readTree)
	}
	if cursor == nil {
		return nil, false
	}
	current, err := cursor.SyncFocus(ctx, request.readFocus)
	position := request.readPosition
	if err != nil || current.Document.ID() != position.Document.ID() {
		return cursor, false
	}
	// A page can be recaptured while Say All is being assembled. Earlier
	// lines retain references from the old tree, so bind the spoken object's
	// identity to the tree that will receive the progress update.
	object, err := cursor.tree.Reference(position.Object.ID())
	if err != nil {
		return cursor, false
	}
	owner, err := cursor.tree.DocumentContext(object)
	if err != nil || owner.TopLevel != current.Document {
		return cursor, false
	}
	snapshot, err := cursor.tree.Resolve(object)
	if err != nil || position.Offset < 0 || position.Offset > snapshot.CharacterCount {
		return cursor, false
	}
	position.Document, position.Object, position.Snapshot = current.Document, object, snapshot
	place := &cursor.places[len(cursor.places)-1]
	place.object, place.offset, place.origin = object, position.Offset, CaretNavigation
	return cursor, true
}

func focusedReadAllLines(content atspi.DocumentContent) []atspi.DocumentLine {
	if content.Text == "" {
		return []atspi.DocumentLine{{Contents: []atspi.DocumentContent{content}}}
	}
	var lines []atspi.DocumentLine
	offset := content.Start
	for _, value := range strings.SplitAfter(content.Text, "\n") {
		part := content
		part.Start, part.End, part.Text = offset, offset+utf8.RuneCountInString(value), value
		offset = part.End
		if strings.TrimSpace(value) != "" {
			lines = append(lines, atspi.DocumentLine{Contents: []atspi.DocumentContent{part}})
		}
	}
	return lines
}