//
//  BlockingObservable+Operators.swift
//  Rx
//
//  Created by Krunoslav Zaher on 10/19/15.
//  Copyright © 2015 Krunoslav Zaher. All rights reserved.
//

import Foundation
#if !RX_NO_MODULE
    import RxSwift
#endif

extension BlockingObservable {
    /**
     Blocks current thread until sequence terminates.

     If sequence terminates with error, terminating error will be thrown.

     - returns: All elements of sequence.
     */
    public func toArray() throws -> [E] {
        var elements: [E] = Array<E>()

        var error: Swift.Error?

        let lock = RunLoopLock(timeout: timeout)

        let d = SingleAssignmentDisposable()

        defer {
            d.dispose()
        }

        lock.dispatch {
            d.disposable = self.source.subscribe { e in
                if d.isDisposed {
                    return
                }
                switch e {
                case .next(let element):
                    elements.append(element)
                case .error(let e):
                    error = e
                    d.dispose()
                    lock.stop()
                case .completed:
                    d.dispose()
                    lock.stop()
                }
            }
        }

        try lock.run()

        if let error = error {
            throw error
        }

        return elements
    }
}

extension BlockingObservable {
    /**
     Blocks current thread until sequence produces first element.

     If sequence terminates with error before producing first element, terminating error will be thrown.

     - returns: First element of sequence. If sequence is empty `nil` is returned.
     */
    public func first() throws -> E? {
        var element: E?

        var error: Swift.Error?

        let d = SingleAssignmentDisposable()

        defer {
            d.dispose()
        }
        
        let lock = RunLoopLock(timeout: timeout)

        lock.dispatch {
            d.disposable = self.source.subscribe { e in
                if d.isDisposed {
                    return
                }

                switch e {
                case .next(let e):
                    if element == nil {
                        element = e
                    }
                    break
                case .error(let e):
                    error = e
                default:
                    break
                }

                d.dispose()
                lock.stop()
            }
        }

        try lock.run()

        if let error = error {
            throw error
        }

        return element
    }
}

extension BlockingObservable {
    /**
     Blocks current thread until sequence terminates.

     If sequence terminates with error, terminating error will be thrown.

     - returns: Last element in the sequence. If sequence is empty `nil` is returned.
     */
    public func last() throws -> E? {
        var element: E?

        var error: Swift.Error?

        let d = SingleAssignmentDisposable()

        defer {
            d.dispose()
        }
        
        let lock = RunLoopLock(timeout: timeout)

        lock.dispatch {
            d.disposable = self.source.subscribe { e in
                if d.isDisposed {
                    return
                }
                switch e {
                case .next(let e):
                    element = e
                    return
                case .error(let e):
                    error = e
                default:
                    break
                }

                d.dispose()
                lock.stop()
            }
        }
        
        try lock.run()
        
        if let error = error {
            throw error
        }
        
        return element
    }
}

extension BlockingObservable {
    /**
     Blocks current thread until sequence terminates.
     
     If sequence terminates with error before producing first element, terminating error will be thrown.
     
     - returns: Returns the only element of an sequence, and reports an error if there is not exactly one element in the observable sequence.
     */
    public func single() throws -> E? {
        return try single { _ in true }
    }

    /**
     Blocks current thread until sequence terminates.
     
     If sequence terminates with error before producing first element, terminating error will be thrown.
     
     - parameter predicate: A function to test each source element for a condition.
     - returns: Returns the only element of an sequence that satisfies the condition in the predicate, and reports an error if there is not exactly one element in the sequence.
     */
    public func single(_ predicate: @escaping (E) throws -> Bool) throws -> E? {
        var element: E?
        
        var error: Swift.Error?
        
        let d = SingleAssignmentDisposable()

        defer {
            d.dispose()
        }
        
        let lock = RunLoopLock(timeout: timeout)
        
        lock.dispatch {
            d.disposable = self.source.subscribe { e in
                if d.isDisposed {
                    return
                }
                switch e {
                case .next(let e):
                    do {
                        if try !predicate(e) {
                            return
                        }
                        if element == nil {
                            element = e
                        } else {
                            throw RxError.moreThanOneElement
                        }
                    } catch (let err) {
                        error = err
                        d.dispose()
                        lock.stop()
                    }
                    return
                case .error(let e):
                    error = e
                case .completed:
                    if element == nil {
                        error = RxError.noElements
                    }
                }

                d.dispose()
                lock.stop()
            }
        }
        
        try lock.run()

        if let error = error {
            throw error
        }
        
        return element
    }
}