'use strict';
const fs = require('fs');
const sourceMap = require('source-map');
const AWS = require('aws-sdk');
const URL = require('url');
const request = require('request');
const wasm = fs.readFileSync(process.env.MAPPING_WASM || '/mappings.wasm');
sourceMap.SourceMapConsumer.initialize({
    "lib/mappings.wasm": wasm
});

console.log(`>sourceMap initialised using ${process.env.MAPPING_WASM || '/mappings.wasm'}`);

function parseSourcemap(sourcemap, event, options, resolve, reject) {
    const getObjectEnd = Date.now();
    try {
        return new sourceMap.SourceMapConsumer(sourcemap)
            .then(consumer => {
                let results = [];
                for (let i = 0; i < event.positions.length; i++) {
                    let original = consumer.originalPositionFor({
                        line: event.positions[i].line,
                        column: event.positions[i].column
                    });
                    let url = URL.parse("");
                    let preview = [];
                    if (original.source) {
                        preview = consumer.sourceContentFor(original.source, true);
                        if (preview !== null) {
                            preview = preview.split("\n")
                                .map((line, i) => [i + 1, line]);
                            if (event.padding) {
                                let start = original.line < event.padding ? 0 : original.line - event.padding;
                                preview = preview.slice(start, original.line + event.padding);
                            }
                        } else {
                            console.log(`[SR] source not found, null preview for: ${original.source}`);
                            preview = []
                        }
                        url = URL.parse(original.source);
                    } else {
                        console.log("[SR] couldn't find original position of: " + JSON.stringify({
                            line: event.positions[i].line,
                            column: event.positions[i].column
                        }));
                    }
                    let result = {
                        "absPath": url.href,
                        "filename": url.pathname,
                        "lineNo": original.line,
                        "colNo": original.column,
                        "function": original.name,
                        "context": preview
                    };
                    // console.log(result);
                    results.push(result);
                }
                consumer = undefined;

                options.sourcemapProcessingTime = (Date.now() - getObjectEnd) / 1000;
                options.sourcemapProcessingTimeUnit = 's';
                if (options.fileSize >= 3 || options.sourcemapProcessingTime > 2) {
                    console.log("[SR] " + JSON.stringify(options));
                }
                // Use this code if you don't use the http event with the LAMBDA-PROXY integration
                return resolve(results);
            })
            .catch(err => {
                return reject(err);
            })
            .finally(() => {
                sourcemap = undefined;
            });
    } catch (err) {
        reject(err);
    }
}

module.exports.sourcemapReader = async event => {
    if (event.isURL) {
        let options = {
            URL: event.key
        };
        return new Promise(function (resolve, reject) {
            const getObjectStart = Date.now();
            return request.get(options.URL, (err, response, sourcemap) => {
                if (err || response.statusCode !== 200) {
                    console.error("[SR] Getting file from URL failed");
                    console.error("err:");
                    console.error(err);
                    console.error("response:");
                    if (err) {
                        return reject(err);
                    }
                    return reject(response);
                }
                const getObjectEnd = Date.now();
                options.fileSize = (response.headers['content-length'] / 1024) / 1024;
                options.fileSizeUnit = 'Mb';
                options.downloadTime = (getObjectEnd - getObjectStart) / 1000;
                options.downloadTimeUnit = 's';
                if (options.fileSize >= 3) {
                    console.log("[SR] large file:" + JSON.stringify(options));
                }
                return parseSourcemap(sourcemap, event, options, resolve, reject);
            });
        });
    } else {
        let s3;
        if (process.env.S3_HOST) {
            s3 = new AWS.S3({
                endpoint: process.env.S3_HOST,
                accessKeyId: process.env.S3_KEY,
                secretAccessKey: process.env.S3_SECRET,
                s3ForcePathStyle: true, // needed with minio?
                signatureVersion: 'v4'
            });
        } else {
            s3 = new AWS.S3({
                'AccessKeyID': process.env.aws_access_key_id,
                'SecretAccessKey': process.env.aws_secret_access_key,
                'Region': process.env.aws_region
            });
        }

        let options = {
            Bucket: event.bucket,
            Key: event.key
        };
        return new Promise(function (resolve, reject) {
            const getObjectStart = Date.now();
            s3.getObject(options, (err, data) => {
                if (err) {
                    console.error("[SR] Get S3 object failed");
                    console.error(err);
                    return reject(err);
                }
                const getObjectEnd = Date.now();
                options.fileSize = (data.ContentLength / 1024) / 1024;
                options.fileSizeUnit = 'Mb';
                options.downloadTime = (getObjectEnd - getObjectStart) / 1000;
                options.downloadTimeUnit = 's';
                if (options.fileSize >= 3) {
                    console.log("[SR] large file:" + JSON.stringify(options));
                }
                let sourcemap = data.Body.toString();
                return parseSourcemap(sourcemap, event, options, resolve, reject);
            });
        });
    }
};