import XCTest
@testable import Model

final class EmptyBoardTests: XCTestCase {
    private var board: Board!
    
    override func setUpWithError() throws {
        super.setUp()
        
        guard let board = Board(columns: 5, rows: 6) else {
            XCTFail()
            return
        }
        
        self.board = board
    }
    
    func testWidth() throws {
        XCTAssertEqual(board.columns, 5)
    }
    
    func testHeight() throws {
        XCTAssertEqual(board.rows, 6)
    }
    
    func testEmptyByDefault() throws {
        XCTAssertNil(board[1, 1])
        let result = board.countPieces()
        XCTAssertEqual(result, 0)
    }
    
    func testCustomSubscript() throws {
        for r in 0..<board.rows {
            for c in 0..<board.columns {
                for p: Player in [.A, .B] {
                    try self.setUpWithError()
                    
                    try self._testCustomSubscript(at: Coords(c, r), player: p)
                    
                    try self.tearDownWithError()
                }
            }
        }
    }
    
    private func _testCustomSubscript(at: Coords, player: Player) throws {
        board[at] = Piece(owner: player)
        
        XCTAssertEqual(board[at]?.owner, player)
    }
    
    func testCounts() throws {
        board[1, 2] = Piece(owner: .B)
        board[0, 2] = Piece(owner: .A)
        board[1, 1] = Piece(owner: .A)
        
        XCTAssertEqual(board.countPieces { piece in piece.owner == .A }, 2)
        XCTAssertEqual(board.countPieces { piece in piece.owner == .B }, 1)
    }
    
    func testInsertsSides() throws {
        for (side, offset, expected): (Direction, Int, (Int, Int)) in [
            (.Top, 0, (0, 0)),
            (.Left, 0, (0, 0)),
            (.Bottom, 0, (0, 5)),
            (.Right, 0, (4, 0)),
            /* ... */
            (.Top, 4, (4, 0)),
            (.Left, 5, (0, 5)),
            (.Bottom, 4, (4, 5)),
            (.Right, 5, (4, 5)),
        ] {
            try self.setUpWithError()
            
            try self._testInsertSide(side: side, offset: offset, expectedCoords: Coords(pair: expected))
            
            try self.tearDownWithError()
        }
    }
    
    private func _testInsertSide(side: Direction, offset: Int, expectedCoords: Coords) throws {
        let result = board.getInsertionCoordinates(from: side, offset: offset)
        
        // Note: Not sure I want Coordinates to be a simple tuple or a struct, as both have advantages that the other dont:
        // Tuples can be initialized like so (col, row) which I find quite handy
        // Structs supports == operators
        // ...
        XCTAssertEqual(result.col, expectedCoords.col)
        XCTAssertEqual(result.row, expectedCoords.row)
    }
    
    func testInsertsFallNoPiece() throws {
        for (from, direction, expected): ((Int, Int), Direction, (Int, Int)) in [
            ((0, 0), .Bottom, (0, 5)),
            ((0, 0), .Left, (0, 0)),
            ((0, 0), .Right, (4, 0)),
            ((0, 0), .Top, (0, 0)),
            /* ... */
            ((4, 5), .Bottom, (4, 5)),
            ((4, 5), .Left, (0, 5)),
            ((4, 5), .Right, (4, 5)),
            ((4, 5), .Top, (4, 0)),
        ] {
            try self.setUpWithError()
            
            try self._testInsertFall(from: Coords(pair: from), dir: direction, expectedCoords: .Border(at: Coords(pair: expected)))
            
            try self.tearDownWithError()
        }
    }
    
    func testInsertsFallOnPiece() throws {
        for (from, direction, (expected, touched)): ((Int, Int), Direction, ((Int, Int), (Int, Int))) in [
            ((0, 0), .Bottom, ((0, 1), (0, 2))),
            ((0, 0), .Right, ((1, 0), (2, 0))),
            ((4, 5), .Left, ((3, 5), (2, 5))),
            ((4, 5), .Top, ((4, 3), (4, 2))),
        ] {
            try self.setUpWithError()
            
            // Place some pieces
            for pos in [
                                (2, 0),
                                (2, 1),
                (0, 2), (1, 2), (2, 2), (3, 2), (4, 2),
                                (2, 3),
                                (2, 4),
                                (2, 5),
            ] {
                // ensure it works with any player
                board[Coords(pair: pos)] = if (pos.0 + pos.1) & 1 == 1 {
                    Piece(owner: .A)
                } else {
                    Piece(owner: .B)
                }
            }
            
            try self._testInsertFall(
                from: Coords(pair: from),
                dir: direction,
                expectedCoords: .Piece(at: Coords(pair: expected), touched: Coords(pair: touched))
            )
            
            try self.tearDownWithError()
        }
    }
    
    private func _testInsertFall(from: Coords, dir: Direction, expectedCoords: Board.FallResult) throws {
        let result = board.fallCoordinates(initialCoords: from, direction: dir)
        
        XCTAssertEqual(result, expectedCoords)
    }
}