//
//  PostViewTests.swift
//  damusTests
//
//  Created by Daniel D’Aquino on 2023-08-19.
//
import Foundation
import XCTest
@testable import damus
import SwiftUI

final class PostViewTests: XCTestCase {
    
    override func setUpWithError() throws {
        // Put setup code here. This method is called before the invocation of each test method in the class.
    }
    
    override func tearDownWithError() throws {
        // Put teardown code here. This method is called after the invocation of each test method in the class.
    }
    
    /// Based on https://github.com/damus-io/damus/issues/1375
    /// Tests whether the editor properly handles mention links after they have been added, to avoid manual editing of attributed links
    func testMentionLinkEditorHandling() throws {
        var content: NSMutableAttributedString

        // Test normal insertion
        checkMentionLinkEditorHandling(content: NSMutableAttributedString(string: "Hello"), replacementText: "@", replacementRange: NSRange(location: 0, length: 0), shouldBeAbleToChangeAutomatically: true)
        checkMentionLinkEditorHandling(content: NSMutableAttributedString(string: "Hello "), replacementText: "@", replacementRange: NSRange(location: 6, length: 0), shouldBeAbleToChangeAutomatically: true)
        checkMentionLinkEditorHandling(content: NSMutableAttributedString(string: "Helo "), replacementText: "l", replacementRange: NSRange(location: 3, length: 0), shouldBeAbleToChangeAutomatically: true)
        
        // Test normal backspacing
        checkMentionLinkEditorHandling(content: NSMutableAttributedString(string: "Hello"), replacementText: "", replacementRange: NSRange(location: 5, length: 1), shouldBeAbleToChangeAutomatically: true)
        checkMentionLinkEditorHandling(content: NSMutableAttributedString(string: "Hello "), replacementText: "", replacementRange: NSRange(location: 6, length: 1), shouldBeAbleToChangeAutomatically: true)
        checkMentionLinkEditorHandling(content: NSMutableAttributedString(string: "Helo "), replacementText: "", replacementRange: NSRange(location: 3, length: 1), shouldBeAbleToChangeAutomatically: true)

        // Test normal insertion after mention link
        content = NSMutableAttributedString(string: "Hello @user ")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 5))
        checkMentionLinkEditorHandling(content: content, replacementText: "a", replacementRange: NSRange(location: 12, length: 0), shouldBeAbleToChangeAutomatically: true)

        // Test insertion right at the end of a mention link, at the end of the text
        content = NSMutableAttributedString(string: "Hello @user")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 5))
        checkMentionLinkEditorHandling(content: content, replacementText: ",", replacementRange: NSRange(location: 11, length: 0), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 12, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello @user,")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 11, effectiveRange: nil))
        })

        // Test insertion right at the end of a mention link, in the middle of the text
        content = NSMutableAttributedString(string: "Hello @user how are you?")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 5))
        checkMentionLinkEditorHandling(content: content, replacementText: ",", replacementRange: NSRange(location: 11, length: 0), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 12, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello @user, how are you?")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 11, effectiveRange: nil))
        })

        // Test insertion in the middle of a mention link to check if the link is removed
        content = NSMutableAttributedString(string: "Hello @user how are you?")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 5))
        checkMentionLinkEditorHandling(content: content, replacementText: "a", replacementRange: NSRange(location: 8, length: 0), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 9, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello @uaser how are you?")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 8, effectiveRange: nil))
        })

        // Test insertion in the middle of a mention link to check if the link is removed, at the end of the text
        content = NSMutableAttributedString(string: "Hello @user")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 5))
        checkMentionLinkEditorHandling(content: content, replacementText: "a", replacementRange: NSRange(location: 8, length: 0), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 9, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello @uaser")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 8, effectiveRange: nil))
        })

        // Test backspacing right at the end of a mention link, at the end of the text
        content = NSMutableAttributedString(string: "Hello @user")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 5))
        checkMentionLinkEditorHandling(content: content, replacementText: "", replacementRange: NSRange(location: 10, length: 1), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 10, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello @use")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 6, effectiveRange: nil))
        })

        // Test adding text right at the start of a mention link, to check that the link is removed
        content = NSMutableAttributedString(string: "Hello @user")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 5))
        checkMentionLinkEditorHandling(content: content, replacementText: "a", replacementRange: NSRange(location: 6, length: 0), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 7, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello a@user")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 7, effectiveRange: nil))
        })

        // Test that removing one link does not affect the other
        content = NSMutableAttributedString(string: "Hello @user1 @user2")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 6))
        content.addAttribute(.link, value: "damus:5678", range: NSRange(location: 13, length: 6))
        checkMentionLinkEditorHandling(content: content, replacementText: "", replacementRange: NSRange(location: 18, length: 1), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 18, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello @user1 @user")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 13, effectiveRange: nil))
            XCTAssertNotNil(newManuallyEditedContent.attribute(.link, at: 6, effectiveRange: nil))
        })

        // Test that replacing a whole range intersecting with two links removes both links
        content = NSMutableAttributedString(string: "Hello @user1 @user2")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 6))
        content.addAttribute(.link, value: "damus:5678", range: NSRange(location: 13, length: 6))
        checkMentionLinkEditorHandling(content: content, replacementText: "a", replacementRange: NSRange(location: 10, length: 4), shouldBeAbleToChangeAutomatically: false, expectedNewCursorIndex: 11, handleNewContent: { newManuallyEditedContent in
            XCTAssertEqual(newManuallyEditedContent.string, "Hello @useauser2")
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 6, effectiveRange: nil))
            XCTAssertNil(newManuallyEditedContent.attribute(.link, at: 11, effectiveRange: nil))
        })

        // Test that replacing a whole range including two links removes both links naturally
        content = NSMutableAttributedString(string: "Hello @user1 @user2, how are you?")
        content.addAttribute(.link, value: "damus:1234", range: NSRange(location: 6, length: 6))
        content.addAttribute(.link, value: "damus:5678", range: NSRange(location: 13, length: 6))
        checkMentionLinkEditorHandling(content: content, replacementText: "", replacementRange: NSRange(location: 5, length: 28), shouldBeAbleToChangeAutomatically: true)
        
    }
}

func checkMentionLinkEditorHandling(
    content: NSMutableAttributedString,
    replacementText: String,
    replacementRange: NSRange,
    shouldBeAbleToChangeAutomatically: Bool,
    expectedNewCursorIndex: Int? = nil,
    handleNewContent: ((NSMutableAttributedString) -> Void)? = nil) {
        let bindingContent: Binding<NSMutableAttributedString> = Binding(get: {
            return content
        }, set: { newValue in
            handleNewContent?(newValue)
        })
        let coordinator: TextViewWrapper.Coordinator = TextViewWrapper.Coordinator(attributedText: bindingContent, getFocusWordForMention: nil, updateCursorPosition: { newCursorIndex in
            if let expectedNewCursorIndex {
                XCTAssertEqual(newCursorIndex, expectedNewCursorIndex)
            }
        })
        let textView = UITextView()
        textView.attributedText = content

        XCTAssertEqual(coordinator.textView(textView, shouldChangeTextIn: replacementRange, replacementText: replacementText), shouldBeAbleToChangeAutomatically, "Expected shouldChangeTextIn to return \(shouldBeAbleToChangeAutomatically), but was \(!shouldBeAbleToChangeAutomatically)")
}