package lsp

import (
	"context"

	"golang.org/x/tools/internal/lsp/protocol"
	"golang.org/x/tools/internal/lsp/source"
)

func (s *Server) foldingRange(ctx context.Context, params *protocol.FoldingRangeParams) ([]protocol.FoldingRange, error) {
	snapshot, fh, ok, err := s.beginFileRequest(ctx, params.TextDocument.URI, source.Go)
	if !ok {
		return nil, err
	}

	ranges, err := source.FoldingRange(ctx, snapshot, fh, snapshot.View().Options().LineFoldingOnly)
	if err != nil {
		return nil, err
	}
	return toProtocolFoldingRanges(ranges)
}

func toProtocolFoldingRanges(ranges []*source.FoldingRangeInfo) ([]protocol.FoldingRange, error) {
	result := make([]protocol.FoldingRange, 0, len(ranges))
	for _, info := range ranges {
		rng, err := info.Range()
		if err != nil {
			return nil, err
		}
		result = append(result, protocol.FoldingRange{
			StartLine:      rng.Start.Line,
			StartCharacter: rng.Start.Character,
			EndLine:        rng.End.Line,
			EndCharacter:   rng.End.Character,
			Kind:           string(info.Kind),
		})
	}
	return result, nil
}