//
//  MongoEvaluator.swift
//  MongoView
//
//  Created by Shadowfacts on 1/12/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import Foundation
import MongoSwift

struct MongoEvaluator {
    
    static let decoder = BSONDecoder()

    static func parse(extendedJSON: String) -> BSON? {
        guard !extendedJSON.isEmpty else {
            return nil
        }
        do {
            return try decoder.decode(BSON.self, from: extendedJSON)
        } catch {
            print("Unable to parse BSON: \(error)")
            return nil
        }
    }
    
    static func eval(command: String, connectingTo connStr: String) -> [BSON] {
        let realCommand = """
Object.prototype.printExtJSON = function() { print(JSON.stringify(this)); };
Array.prototype.printExtJSON = function() { this.map(JSON.stringify).forEach(it => print(it)); };
\(command).printExtJSON()
"""
        print("Running command \"\(command)\" against \(connStr)")
        
        let mongoOutputPipe = Pipe()

        let mongoProcess = Process()
        mongoProcess.launchPath = "/usr/local/bin/mongo"
        mongoProcess.arguments = [connStr, "--quiet", "--norc", "--eval", realCommand]
        mongoProcess.standardOutput = mongoOutputPipe
        mongoProcess.launch()
        
        let mongoOutputHandle = mongoOutputPipe.fileHandleForReading
        
        var strs = [String]()
        var data: Data!
        repeat {
            data = mongoOutputHandle.availableData
            strs.append(String(data: data, encoding: .utf8)!)
        } while (data.count > 0)
        mongoOutputHandle.closeFile()
        
        let lines = strs.joined(separator: "").components(separatedBy: "\n")
        return lines.compactMap(parse(extendedJSON:))
    }
    
}