package p.studio.lsp;

import p.studio.compiler.pbs.lexer.PbsToken;
import p.studio.compiler.pbs.lexer.PbsTokenKind;
import p.studio.lsp.dtos.LspDefinitionTargetDTO;
import p.studio.lsp.dtos.LspSymbolDTO;
import p.studio.lsp.messages.LspDefinitionRequest;
import p.studio.lsp.messages.LspDefinitionResult;
import p.studio.lsp.messages.SemanticSession;

import java.nio.file.Path;
import java.util.List;

import static p.studio.lsp.LspSemanticUtilities.normalize;
import static p.studio.lsp.LspSemanticUtilities.tokenAt;

class LspSemanticDefinitionService {

    LspDefinitionResult definition(
            final SemanticSession session,
            final LspDefinitionRequest request) {
        final List<LspDefinitionTargetDTO> targets = resolveDefinitionTargets(session, request);
        return new LspDefinitionResult(request.documentPath(), request.offset(), targets);
    }

    private List<LspDefinitionTargetDTO> resolveDefinitionTargets(
            final SemanticSession session,
            final LspDefinitionRequest request) {
        final Path documentPath = normalize(request.documentPath());
        final List<PbsToken> tokens = session.tokensByDocument().getOrDefault(documentPath, List.of());
        final PbsToken activeToken = tokenAt(tokens, request.offset());
        if (activeToken == null || activeToken.kind() != PbsTokenKind.IDENTIFIER) {
            return List.of();
        }
        final String lexeme = activeToken.lexeme();
        final List<LspSymbolDTO> sameDocumentMatches = session.symbolsByName().getOrDefault(lexeme, List.of()).stream()
                .filter(symbol -> symbol.documentPath().equals(documentPath))
                .toList();
        final List<LspSymbolDTO> effectiveMatches = sameDocumentMatches.isEmpty()
                ? session.symbolsByName().getOrDefault(lexeme, List.of())
                : sameDocumentMatches;
        return effectiveMatches.stream()
                .map(symbol -> new LspDefinitionTargetDTO(symbol.name(), symbol.documentPath(), symbol.range()))
                .toList();
    }
}