"use strict";

import * as path from "path";

const LineByLineReader = require("line-by-line");

export interface ITryStatement {

StartLineNumber: number;

EndLineNumber: number;

Exceptions: string[];

}

interface ITryStatementEx extends ITryStatement {

Column: number;

}

export function ExtractTryStatements(pythonFile: string): Promise<ITryStatement[]> {

return new Promise<ITryStatement[]>(resolve => {

let lr = new LineByLineReader(pythonFile);

let lineNumber = 0;

let tryStatements: ITryStatementEx[] = [];

let tryColumnBlocks = new Map<number, ITryStatementEx>();

lr.on("error", function (err) {

resolve(tryStatements);

});

lr.on("line", function (line) {

lineNumber++;

// Valid parts of a try block include

// try:, except <error>:, except: else: finally:

// Anything other than this in the same column indicates a termination of the try block

let trimmedLine = line.trim();

let matches = line.match(/^\s*try(\s*):/);

if (matches !== null && matches.length > 0) {

let column = line.indexOf("try");

if (column === -1) {

return;

}

// If the new try starts at the same column

// Then the previous try block has ended

if (tryColumnBlocks.has(column)) {

let tryBlockClosed = tryColumnBlocks.get(column);

tryColumnBlocks.delete(column);

tryStatements.push(tryBlockClosed);

}

let tryStatement: ITryStatementEx = {

Column: column,

EndLineNumber: 0,

Exceptions: [],

StartLineNumber: lineNumber

};

tryColumnBlocks.set(column, tryStatement);

return;

}

// look for excepts

matches = line.match(/^\s*except/);

if (matches !== null && matches.length > 0 &&

(trimmedLine.startsWith("except ") || trimmedLine.startsWith("except:"))) {

// Oops something has gone wrong

if (tryColumnBlocks.size === 0) {

resolve(tryStatements);

lr.close();

return;

}

let column = line.indexOf("except");

// Do we have a try block for this same column

if (!tryColumnBlocks.has(column)) {

return;

}

let currentTryBlock = tryColumnBlocks.get(column);

let exceptions = extractExceptions(line);

currentTryBlock.Exceptions = currentTryBlock.Exceptions.concat(exceptions);

if (currentTryBlock.EndLineNumber === 0) {

currentTryBlock.EndLineNumber = lineNumber;

}

return;

}

// look for else

matches = line.match(/^\s*else(\s*):/);

if (matches !== null && matches.length > 0 &&

(trimmedLine.startsWith("else ") || trimmedLine.startsWith("else:"))) {

// This is possibly an if else...

if (tryColumnBlocks.size === 0) {

return;

}

let column = line.indexOf("else");

// Check if we have a try associated with this column

// If not found, this is probably an if else block or something else

if (!tryColumnBlocks.has(column)) {

return;

}

// Else marks the end of the try block (of course there could be a finally too)

let currentTryBlock = tryColumnBlocks.get(column);

if (currentTryBlock.EndLineNumber === 0) {

currentTryBlock.EndLineNumber = lineNumber;

}

tryColumnBlocks.delete(column);

tryStatements.push(currentTryBlock);

return;

}

// look for finally

matches = line.match(/^\s*finally(\s*):/);

if (matches !== null && matches.length > 0 &&

(trimmedLine.startsWith("finally ") || trimmedLine.startsWith("finally:"))) {

let column = line.indexOf("finally");

// Oops something has gone wrong, or we cleared the previous

// Try block because we encountered an else

if (tryColumnBlocks.size === 0) {

return;

}

// If this column doesn't match the current exception block, then it is likely we encountered an else for the try block..

// & we closed it off

// So don't treat it as an exception, but proceed

if (!tryColumnBlocks.has(column)) {

return;

}

// Finally marks the end of the try block

let currentTryBlock = tryColumnBlocks.get(column);

if (currentTryBlock.EndLineNumber === 0) {

currentTryBlock.EndLineNumber = lineNumber;

}

tryColumnBlocks.delete(column);

tryStatements.push(currentTryBlock);

}

});

lr.on("end", function () {

// All try blocks that haven't been popped can be popped now

// Only if their line numbers have valid end lines

tryColumnBlocks.forEach(tryBlock => {

if (tryBlock.EndLineNumber > 0) {

tryStatements.push(tryBlock);

}

});

resolve(tryStatements);

});

});

}

const EXCEPT_LENGTH = "except".length;

function extractExceptions(line: string): string[] {

let matches = line.match(/^\s*except(\s*):/);

if (matches !== null && matches.length > 0) {

return [];

}

// Remove brackets and : from this

line = line.trim().substring(EXCEPT_LENGTH);

line = line.substring(0, line.indexOf(":"));

line = line.replace(/[\(\)]/g, "");

let exceptions = [];

line.split(",").forEach(ex => {

ex = ex.trim();

if (ex.length === 0) {

return;

}

if (ex.indexOf(" as ") > 0) {

exceptions.push(ex.substring(0, ex.indexOf(" as ")).trim());

}

else {

exceptions.push(ex);

}

});

return exceptions;

}