/* @internal */
namespace ts.DocumentHighlights {
    export function getDocumentHighlights(typeChecker: TypeChecker, cancellationToken: CancellationToken, sourceFile: SourceFile, position: number, sourceFilesToSearch: SourceFile[]): DocumentHighlights[] {
        const node = getTouchingWord(sourceFile, position);
        return node && (getSemanticDocumentHighlights(node, typeChecker, cancellationToken, sourceFilesToSearch) || getSyntacticDocumentHighlights(node, sourceFile));
    }

    function getHighlightSpanForNode(node: Node, sourceFile: SourceFile): HighlightSpan {
        const start = node.getStart(sourceFile);
        const end = node.getEnd();

        return {
            fileName: sourceFile.fileName,
            textSpan: createTextSpanFromBounds(start, end),
            kind: HighlightSpanKind.none
        };
    }

    function getSemanticDocumentHighlights(node: Node, typeChecker: TypeChecker, cancellationToken: CancellationToken, sourceFilesToSearch: SourceFile[]): DocumentHighlights[] {
        const referencedSymbols = FindAllReferences.getReferencedSymbolsForNode(typeChecker, cancellationToken, node, sourceFilesToSearch);
        return referencedSymbols && convertReferencedSymbols(referencedSymbols);
    }

    function convertReferencedSymbols(referencedSymbols: ReferencedSymbol[]): DocumentHighlights[] {
        const fileNameToDocumentHighlights = createMap<DocumentHighlights>();
        const result: DocumentHighlights[] = [];
        for (const referencedSymbol of referencedSymbols) {
            for (const referenceEntry of referencedSymbol.references) {
                const fileName = referenceEntry.fileName;
                let documentHighlights = fileNameToDocumentHighlights.get(fileName);
                if (!documentHighlights) {
                    documentHighlights = { fileName, highlightSpans: [] };

                    fileNameToDocumentHighlights.set(fileName, documentHighlights);
                    result.push(documentHighlights);
                }

                documentHighlights.highlightSpans.push({
                    textSpan: referenceEntry.textSpan,
                    kind: referenceEntry.isWriteAccess ? HighlightSpanKind.writtenReference : HighlightSpanKind.reference
                });
            }
        }

        return result;
    }

    function getSyntacticDocumentHighlights(node: Node, sourceFile: SourceFile): DocumentHighlights[] {
        const highlightSpans = getHighlightSpans(node, sourceFile);
        if (!highlightSpans || highlightSpans.length === 0) {
            return undefined;
        }

        return [{ fileName: sourceFile.fileName, highlightSpans }];
    }

    // returns true if 'node' is defined and has a matching 'kind'.
    function hasKind(node: Node, kind: SyntaxKind) {
        return node !== undefined && node.kind === kind;
    }

    // Null-propagating 'parent' function.
    function parent(node: Node): Node {
        return node && node.parent;
    }

    function getHighlightSpans(node: Node, sourceFile: SourceFile): HighlightSpan[] {
        if (!node) {
            return undefined;
        }

        switch (node.kind) {
            case SyntaxKind.IfKeyword:
            case SyntaxKind.ElseKeyword:
                if (hasKind(node.parent, SyntaxKind.IfStatement)) {
                    return getIfElseOccurrences(<IfStatement>node.parent, sourceFile);
                }
                break;
            case SyntaxKind.ReturnKeyword:
                if (hasKind(node.parent, SyntaxKind.ReturnStatement)) {
                    return highlightSpans(getReturnOccurrences(<ReturnStatement>node.parent));
                }
                break;
            case SyntaxKind.ThrowKeyword:
                if (hasKind(node.parent, SyntaxKind.ThrowStatement)) {
                    return highlightSpans(getThrowOccurrences(<ThrowStatement>node.parent));
                }
                break;
            case SyntaxKind.TryKeyword:
            case SyntaxKind.CatchKeyword:
            case SyntaxKind.FinallyKeyword:
                const tryStatement = node.kind === SyntaxKind.CatchKeyword ? parent(parent(node)) : parent(node);
                if (hasKind(tryStatement, SyntaxKind.TryStatement)) {
                    return highlightSpans(getTryCatchFinallyOccurrences(<TryStatement>tryStatement, sourceFile));
                }
                break;
            case SyntaxKind.SwitchKeyword:
                if (hasKind(node.parent, SyntaxKind.SwitchStatement)) {
                    return highlightSpans(getSwitchCaseDefaultOccurrences(<SwitchStatement>node.parent));
                }
                break;
            case SyntaxKind.CaseKeyword:
            case SyntaxKind.DefaultKeyword:
                if (hasKind(parent(parent(parent(node))), SyntaxKind.SwitchStatement)) {
                    return highlightSpans(getSwitchCaseDefaultOccurrences(<SwitchStatement>node.parent.parent.parent));
                }
                break;
            case SyntaxKind.BreakKeyword:
            case SyntaxKind.ContinueKeyword:
                if (hasKind(node.parent, SyntaxKind.BreakStatement) || hasKind(node.parent, SyntaxKind.ContinueStatement)) {
                    return highlightSpans(getBreakOrContinueStatementOccurrences(<BreakOrContinueStatement>node.parent));
                }
                break;
            case SyntaxKind.ForKeyword:
                if (hasKind(node.parent, SyntaxKind.ForStatement) ||
                    hasKind(node.parent, SyntaxKind.ForInStatement) ||
                    hasKind(node.parent, SyntaxKind.ForOfStatement)) {
                    return highlightSpans(getLoopBreakContinueOccurrences(<IterationStatement>node.parent));
                }
                break;
            case SyntaxKind.WhileKeyword:
            case SyntaxKind.DoKeyword:
                if (hasKind(node.parent, SyntaxKind.WhileStatement) || hasKind(node.parent, SyntaxKind.DoStatement)) {
                    return highlightSpans(getLoopBreakContinueOccurrences(<IterationStatement>node.parent));
                }
                break;
            case SyntaxKind.ConstructorKeyword:
                if (hasKind(node.parent, SyntaxKind.Constructor)) {
                    return highlightSpans(getConstructorOccurrences(<ConstructorDeclaration>node.parent));
                }
                break;
            case SyntaxKind.GetKeyword:
            case SyntaxKind.SetKeyword:
                if (hasKind(node.parent, SyntaxKind.GetAccessor) || hasKind(node.parent, SyntaxKind.SetAccessor)) {
                    return highlightSpans(getGetAndSetOccurrences(<AccessorDeclaration>node.parent));
                }
                break;
            default:
                if (isModifierKind(node.kind) && node.parent &&
                    (isDeclaration(node.parent) || node.parent.kind === SyntaxKind.VariableStatement)) {
                    return highlightSpans(getModifierOccurrences(node.kind, node.parent));
                }
        }

        function highlightSpans(nodes: Node[]): HighlightSpan[] {
            return nodes && nodes.map(node => getHighlightSpanForNode(node, sourceFile));
        }
    }

    /**
     * Aggregates all throw-statements within this node *without* crossing
     * into function boundaries and try-blocks with catch-clauses.
     */
    function aggregateOwnedThrowStatements(node: Node): ThrowStatement[] {
        const statementAccumulator: ThrowStatement[] = [];
        aggregate(node);
        return statementAccumulator;

        function aggregate(node: Node): void {
            if (node.kind === SyntaxKind.ThrowStatement) {
                statementAccumulator.push(<ThrowStatement>node);
            }
            else if (node.kind === SyntaxKind.TryStatement) {
                const tryStatement = <TryStatement>node;

                if (tryStatement.catchClause) {
                    aggregate(tryStatement.catchClause);
                }
                else {
                    // Exceptions thrown within a try block lacking a catch clause
                    // are "owned" in the current context.
                    aggregate(tryStatement.tryBlock);
                }

                if (tryStatement.finallyBlock) {
                    aggregate(tryStatement.finallyBlock);
                }
            }
            // Do not cross function boundaries.
            else if (!isFunctionLike(node)) {
                forEachChild(node, aggregate);
            }
        }
    }

    /**
     * For lack of a better name, this function takes a throw statement and returns the
     * nearest ancestor that is a try-block (whose try statement has a catch clause),
     * function-block, or source file.
     */
    function getThrowStatementOwner(throwStatement: ThrowStatement): Node {
        let child: Node = throwStatement;

        while (child.parent) {
            const parent = child.parent;

            if (isFunctionBlock(parent) || parent.kind === SyntaxKind.SourceFile) {
                return parent;
            }

            // A throw-statement is only owned by a try-statement if the try-statement has
            // a catch clause, and if the throw-statement occurs within the try block.
            if (parent.kind === SyntaxKind.TryStatement) {
                const tryStatement = <TryStatement>parent;

                if (tryStatement.tryBlock === child && tryStatement.catchClause) {
                    return child;
                }
            }

            child = parent;
        }

        return undefined;
    }

    function aggregateAllBreakAndContinueStatements(node: Node): BreakOrContinueStatement[] {
        const statementAccumulator: BreakOrContinueStatement[] = [];
        aggregate(node);
        return statementAccumulator;

        function aggregate(node: Node): void {
            if (node.kind === SyntaxKind.BreakStatement || node.kind === SyntaxKind.ContinueStatement) {
                statementAccumulator.push(<BreakOrContinueStatement>node);
            }
            // Do not cross function boundaries.
            else if (!isFunctionLike(node)) {
                forEachChild(node, aggregate);
            }
        }
    }

    function ownsBreakOrContinueStatement(owner: Node, statement: BreakOrContinueStatement): boolean {
        const actualOwner = getBreakOrContinueOwner(statement);

        return actualOwner && actualOwner === owner;
    }

    function getBreakOrContinueOwner(statement: BreakOrContinueStatement): Node {
        for (let node = statement.parent; node; node = node.parent) {
            switch (node.kind) {
                case SyntaxKind.SwitchStatement:
                    if (statement.kind === SyntaxKind.ContinueStatement) {
                        continue;
                    }
                // Fall through.
                case SyntaxKind.ForStatement:
                case SyntaxKind.ForInStatement:
                case SyntaxKind.ForOfStatement:
                case SyntaxKind.WhileStatement:
                case SyntaxKind.DoStatement:
                    if (!statement.label || isLabeledBy(node, statement.label.text)) {
                        return node;
                    }
                    break;
                default:
                    // Don't cross function boundaries.
                    if (isFunctionLike(node)) {
                        return undefined;
                    }
                    break;
            }
        }

        return undefined;
    }

    function getModifierOccurrences(modifier: SyntaxKind, declaration: Node): Node[] {
        const container = declaration.parent;

        // Make sure we only highlight the keyword when it makes sense to do so.
        if (isAccessibilityModifier(modifier)) {
            if (!(container.kind === SyntaxKind.ClassDeclaration ||
                container.kind === SyntaxKind.ClassExpression ||
                (declaration.kind === SyntaxKind.Parameter && hasKind(container, SyntaxKind.Constructor)))) {
                return undefined;
            }
        }
        else if (modifier === SyntaxKind.StaticKeyword) {
            if (!(container.kind === SyntaxKind.ClassDeclaration || container.kind === SyntaxKind.ClassExpression)) {
                return undefined;
            }
        }
        else if (modifier === SyntaxKind.ExportKeyword || modifier === SyntaxKind.DeclareKeyword) {
            if (!(container.kind === SyntaxKind.ModuleBlock || container.kind === SyntaxKind.SourceFile)) {
                return undefined;
            }
        }
        else if (modifier === SyntaxKind.AbstractKeyword) {
            if (!(container.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.ClassDeclaration)) {
                return undefined;
            }
        }
        else {
            // unsupported modifier
            return undefined;
        }

        const keywords: Node[] = [];
        const modifierFlag: ModifierFlags = getFlagFromModifier(modifier);

        let nodes: Node[];
        switch (container.kind) {
            case SyntaxKind.ModuleBlock:
            case SyntaxKind.SourceFile:
                // Container is either a class declaration or the declaration is a classDeclaration
                if (modifierFlag & ModifierFlags.Abstract) {
                    nodes = (<Node[]>(<ClassDeclaration>declaration).members).concat(declaration);
                }
                else {
                    nodes = (<Block>container).statements;
                }
                break;
            case SyntaxKind.Constructor:
                nodes = (<Node[]>(<ConstructorDeclaration>container).parameters).concat(
                    (<ClassDeclaration>container.parent).members);
                break;
            case SyntaxKind.ClassDeclaration:
            case SyntaxKind.ClassExpression:
                nodes = (<ClassLikeDeclaration>container).members;

                // If we're an accessibility modifier, we're in an instance member and should search
                // the constructor's parameter list for instance members as well.
                if (modifierFlag & ModifierFlags.AccessibilityModifier) {
                    const constructor = forEach((<ClassLikeDeclaration>container).members, member => {
                        return member.kind === SyntaxKind.Constructor && <ConstructorDeclaration>member;
                    });

                    if (constructor) {
                        nodes = nodes.concat(constructor.parameters);
                    }
                }
                else if (modifierFlag & ModifierFlags.Abstract) {
                    nodes = nodes.concat(container);
                }
                break;
            default:
                Debug.fail("Invalid container kind.");
        }

        forEach(nodes, node => {
            if (getModifierFlags(node) & modifierFlag) {
                forEach(node.modifiers, child => pushKeywordIf(keywords, child, modifier));
            }
        });

        return keywords;

        function getFlagFromModifier(modifier: SyntaxKind) {
            switch (modifier) {
                case SyntaxKind.PublicKeyword:
                    return ModifierFlags.Public;
                case SyntaxKind.PrivateKeyword:
                    return ModifierFlags.Private;
                case SyntaxKind.ProtectedKeyword:
                    return ModifierFlags.Protected;
                case SyntaxKind.StaticKeyword:
                    return ModifierFlags.Static;
                case SyntaxKind.ExportKeyword:
                    return ModifierFlags.Export;
                case SyntaxKind.DeclareKeyword:
                    return ModifierFlags.Ambient;
                case SyntaxKind.AbstractKeyword:
                    return ModifierFlags.Abstract;
                default:
                    Debug.fail();
            }
        }
    }

    function pushKeywordIf(keywordList: Node[], token: Node, ...expected: SyntaxKind[]): boolean {
        if (token && contains(expected, token.kind)) {
            keywordList.push(token);
            return true;
        }

        return false;
    }

    function getGetAndSetOccurrences(accessorDeclaration: AccessorDeclaration): Node[] {
        const keywords: Node[] = [];

        tryPushAccessorKeyword(accessorDeclaration.symbol, SyntaxKind.GetAccessor);
        tryPushAccessorKeyword(accessorDeclaration.symbol, SyntaxKind.SetAccessor);

        return keywords;

        function tryPushAccessorKeyword(accessorSymbol: Symbol, accessorKind: SyntaxKind): void {
            const accessor = getDeclarationOfKind(accessorSymbol, accessorKind);

            if (accessor) {
                forEach(accessor.getChildren(), child => pushKeywordIf(keywords, child, SyntaxKind.GetKeyword, SyntaxKind.SetKeyword));
            }
        }
    }

    function getConstructorOccurrences(constructorDeclaration: ConstructorDeclaration): Node[] {
        const declarations = constructorDeclaration.symbol.getDeclarations();

        const keywords: Node[] = [];

        forEach(declarations, declaration => {
            forEach(declaration.getChildren(), token => {
                return pushKeywordIf(keywords, token, SyntaxKind.ConstructorKeyword);
            });
        });

        return keywords;
    }

    function getLoopBreakContinueOccurrences(loopNode: IterationStatement): Node[] {
        const keywords: Node[] = [];

        if (pushKeywordIf(keywords, loopNode.getFirstToken(), SyntaxKind.ForKeyword, SyntaxKind.WhileKeyword, SyntaxKind.DoKeyword)) {
            // If we succeeded and got a do-while loop, then start looking for a 'while' keyword.
            if (loopNode.kind === SyntaxKind.DoStatement) {
                const loopTokens = loopNode.getChildren();

                for (let i = loopTokens.length - 1; i >= 0; i--) {
                    if (pushKeywordIf(keywords, loopTokens[i], SyntaxKind.WhileKeyword)) {
                        break;
                    }
                }
            }
        }

        const breaksAndContinues = aggregateAllBreakAndContinueStatements(loopNode.statement);

        forEach(breaksAndContinues, statement => {
            if (ownsBreakOrContinueStatement(loopNode, statement)) {
                pushKeywordIf(keywords, statement.getFirstToken(), SyntaxKind.BreakKeyword, SyntaxKind.ContinueKeyword);
            }
        });

        return keywords;
    }

    function getBreakOrContinueStatementOccurrences(breakOrContinueStatement: BreakOrContinueStatement): Node[] {
        const owner = getBreakOrContinueOwner(breakOrContinueStatement);

        if (owner) {
            switch (owner.kind) {
                case SyntaxKind.ForStatement:
                case SyntaxKind.ForInStatement:
                case SyntaxKind.ForOfStatement:
                case SyntaxKind.DoStatement:
                case SyntaxKind.WhileStatement:
                    return getLoopBreakContinueOccurrences(<IterationStatement>owner);
                case SyntaxKind.SwitchStatement:
                    return getSwitchCaseDefaultOccurrences(<SwitchStatement>owner);

            }
        }

        return undefined;
    }

    function getSwitchCaseDefaultOccurrences(switchStatement: SwitchStatement): Node[] {
        const keywords: Node[] = [];

        pushKeywordIf(keywords, switchStatement.getFirstToken(), SyntaxKind.SwitchKeyword);

        // Go through each clause in the switch statement, collecting the 'case'/'default' keywords.
        forEach(switchStatement.caseBlock.clauses, clause => {
            pushKeywordIf(keywords, clause.getFirstToken(), SyntaxKind.CaseKeyword, SyntaxKind.DefaultKeyword);

            const breaksAndContinues = aggregateAllBreakAndContinueStatements(clause);

            forEach(breaksAndContinues, statement => {
                if (ownsBreakOrContinueStatement(switchStatement, statement)) {
                    pushKeywordIf(keywords, statement.getFirstToken(), SyntaxKind.BreakKeyword);
                }
            });
        });

        return keywords;
    }

    function getTryCatchFinallyOccurrences(tryStatement: TryStatement, sourceFile: SourceFile): Node[] {
        const keywords: Node[] = [];

        pushKeywordIf(keywords, tryStatement.getFirstToken(), SyntaxKind.TryKeyword);

        if (tryStatement.catchClause) {
            pushKeywordIf(keywords, tryStatement.catchClause.getFirstToken(), SyntaxKind.CatchKeyword);
        }

        if (tryStatement.finallyBlock) {
            const finallyKeyword = findChildOfKind(tryStatement, SyntaxKind.FinallyKeyword, sourceFile);
            pushKeywordIf(keywords, finallyKeyword, SyntaxKind.FinallyKeyword);
        }

        return keywords;
    }

    function getThrowOccurrences(throwStatement: ThrowStatement): Node[] {
        const owner = getThrowStatementOwner(throwStatement);

        if (!owner) {
            return undefined;
        }

        const keywords: Node[] = [];

        forEach(aggregateOwnedThrowStatements(owner), throwStatement => {
            pushKeywordIf(keywords, throwStatement.getFirstToken(), SyntaxKind.ThrowKeyword);
        });

        // If the "owner" is a function, then we equate 'return' and 'throw' statements in their
        // ability to "jump out" of the function, and include occurrences for both.
        if (isFunctionBlock(owner)) {
            forEachReturnStatement(<Block>owner, returnStatement => {
                pushKeywordIf(keywords, returnStatement.getFirstToken(), SyntaxKind.ReturnKeyword);
            });
        }

        return keywords;
    }

    function getReturnOccurrences(returnStatement: ReturnStatement): Node[] {
        const func = <FunctionLikeDeclaration>getContainingFunction(returnStatement);

        // If we didn't find a containing function with a block body, bail out.
        if (!(func && hasKind(func.body, SyntaxKind.Block))) {
            return undefined;
        }

        const keywords: Node[] = [];
        forEachReturnStatement(<Block>func.body, returnStatement => {
            pushKeywordIf(keywords, returnStatement.getFirstToken(), SyntaxKind.ReturnKeyword);
        });

        // Include 'throw' statements that do not occur within a try block.
        forEach(aggregateOwnedThrowStatements(func.body), throwStatement => {
            pushKeywordIf(keywords, throwStatement.getFirstToken(), SyntaxKind.ThrowKeyword);
        });

        return keywords;
    }

    function getIfElseOccurrences(ifStatement: IfStatement, sourceFile: SourceFile): HighlightSpan[] {
        const keywords: Node[] = [];

        // Traverse upwards through all parent if-statements linked by their else-branches.
        while (hasKind(ifStatement.parent, SyntaxKind.IfStatement) && (<IfStatement>ifStatement.parent).elseStatement === ifStatement) {
            ifStatement = <IfStatement>ifStatement.parent;
        }

        // Now traverse back down through the else branches, aggregating if/else keywords of if-statements.
        while (ifStatement) {
            const children = ifStatement.getChildren();
            pushKeywordIf(keywords, children[0], SyntaxKind.IfKeyword);

            // Generally the 'else' keyword is second-to-last, so we traverse backwards.
            for (let i = children.length - 1; i >= 0; i--) {
                if (pushKeywordIf(keywords, children[i], SyntaxKind.ElseKeyword)) {
                    break;
                }
            }

            if (!hasKind(ifStatement.elseStatement, SyntaxKind.IfStatement)) {
                break;
            }

            ifStatement = <IfStatement>ifStatement.elseStatement;
        }

        const result: HighlightSpan[] = [];

        // We'd like to highlight else/ifs together if they are only separated by whitespace
        // (i.e. the keywords are separated by no comments, no newlines).
        for (let i = 0; i < keywords.length; i++) {
            if (keywords[i].kind === SyntaxKind.ElseKeyword && i < keywords.length - 1) {
                const elseKeyword = keywords[i];
                const ifKeyword = keywords[i + 1]; // this *should* always be an 'if' keyword.

                let shouldCombindElseAndIf = true;

                // Avoid recalculating getStart() by iterating backwards.
                for (let j = ifKeyword.getStart() - 1; j >= elseKeyword.end; j--) {
                    if (!isWhiteSpaceSingleLine(sourceFile.text.charCodeAt(j))) {
                        shouldCombindElseAndIf = false;
                        break;
                    }
                }

                if (shouldCombindElseAndIf) {
                    result.push({
                        fileName: sourceFile.fileName,
                        textSpan: createTextSpanFromBounds(elseKeyword.getStart(), ifKeyword.end),
                        kind: HighlightSpanKind.reference
                    });
                    i++; // skip the next keyword
                    continue;
                }
            }

            // Ordinary case: just highlight the keyword.
            result.push(getHighlightSpanForNode(keywords[i], sourceFile));
        }

        return result;
    }

    /**
     * Whether or not a 'node' is preceded by a label of the given string.
     * Note: 'node' cannot be a SourceFile.
     */
    function isLabeledBy(node: Node, labelName: string) {
        for (let owner = node.parent; owner.kind === SyntaxKind.LabeledStatement; owner = owner.parent) {
            if ((<LabeledStatement>owner).label.text === labelName) {
                return true;
            }
        }

        return false;
    }
}
