import SwiftUI
import UIKit
import Runestone

struct RunestoneEditorView: UIViewRepresentable {

    @Binding var content:     String
    @Binding var textViewRef: Runestone.TextView?
    let filePath:             String
    let theme:                any Theme
    let showLineNumbers:      Bool
    let lineWrapping:         Bool
    let indentWidth:          Int
    var diagnosticRanges:     [DiagnosticRange] = []
    var onContentChange:      ((String) -> Void)?
    var onCursorPositionChange: ((Int, Int) -> Void)?
    @ObservedObject var completionController: CompletionController

    func makeCoordinator() -> Coordinator { Coordinator(self) }

    func makeUIView(context: Context) -> Runestone.TextView {
        let tv = Runestone.TextView()
        configureAppearance(tv); configureEditing(tv)
        tv.editorDelegate = context.coordinator
        completionController.attach(to: tv)
        DispatchQueue.main.async { textViewRef = tv }
        loadState(into: tv)
        return tv
    }

    func updateUIView(_ tv: Runestone.TextView, context: Context) {
        if tv.text != content && !context.coordinator.isEditing { loadState(into: tv) }
        tv.showLineNumbers       = showLineNumbers
        tv.isLineWrappingEnabled = lineWrapping
        tv.indentStrategy        = indentWidth == 0 ? .tab : .space(length: indentWidth)
        applyDiagnostics(to: tv)
    }

    private func loadState(into tv: Runestone.TextView) {
        let lang = LanguageDetector.language(for: filePath)
        let capturedContent = content; let capturedTheme = theme
        Task.detached(priority: .userInitiated) {
            let state = TextViewState(text: capturedContent, theme: capturedTheme,
                                      language: lang.map { TreeSitterLanguageMode(language: $0) })
            await MainActor.run { tv.setState(state) }
        }
    }

    private func configureAppearance(_ tv: Runestone.TextView) {
        tv.backgroundColor       = UIColor(hex: "#1E1E1E")
        tv.showLineNumbers       = showLineNumbers
        tv.showSpaces            = false; tv.showTabs = false; tv.showLineBreaks = false
        tv.isLineWrappingEnabled = lineWrapping
        tv.highlightSelectedLine = true
        tv.lineHeightMultiplier  = 1.4; tv.kern = 0.3
        tv.contentInset          = UIEdgeInsets(top: 8, left: 0, bottom: 120, right: 0)
        tv.verticalOverscrollFactor = 0.5
    }

    private func configureEditing(_ tv: Runestone.TextView) {
        tv.isEditable = true; tv.autocorrectionType = .no; tv.autocapitalizationType = .none
        tv.smartDashesType = .no; tv.smartQuotesType = .no
        tv.smartInsertDeleteType = .no; tv.spellCheckingType = .no
        tv.characterPairs = [
            BasicCharacterPair(leading: "(", trailing: ")"),
            BasicCharacterPair(leading: "[", trailing: "]"),
            BasicCharacterPair(leading: "{", trailing: "}"),
            BasicCharacterPair(leading: "\"", trailing: "\""),
        ]
        tv.characterPairTrailingComponentDeletionMode = .immediatelyFollowingLeadingComponent
        tv.indentStrategy = indentWidth == 0 ? .tab : .space(length: indentWidth)
    }

    private func applyDiagnostics(to tv: Runestone.TextView) {
        guard !diagnosticRanges.isEmpty else { tv.setHighlightedRanges([]); return }
        let highlights: [HighlightedRange] = diagnosticRanges.compactMap { diag in
            guard let range = tv.range(atLine: diag.line, column: diag.column) else { return nil }
            let color: UIColor = diag.severity == .error ? UIColor(hex: "#F44747") : UIColor(hex: "#CCA700")
            return HighlightedRange(range: range, color: color, cornerRadius: 0, underlineStyle: .single)
        }
        tv.setHighlightedRanges(highlights)
    }

    // MARK: - Coordinator

    final class Coordinator: NSObject, TextViewDelegate {
        var parent: RunestoneEditorView
        var isEditing = false
        init(_ parent: RunestoneEditorView) { self.parent = parent }

        func textViewDidChange(_ tv: Runestone.TextView) {
            isEditing = true
            parent.content = tv.text
            parent.onContentChange?(tv.text)
            parent.completionController.textDidChange(in: tv, filePath: parent.filePath)
            isEditing = false
        }

        func textViewDidChangeSelection(_ tv: Runestone.TextView) {
            guard let sel = tv.selectedRange, let loc = tv.textLocation(at: sel.location) else { return }
            parent.onCursorPositionChange?(loc.lineNumber, loc.column)
            if !isEditing { parent.completionController.dismiss() }
        }

        func textViewDidBeginEditing(_ tv: Runestone.TextView) { isEditing = true }
        func textViewDidEndEditing(_ tv: Runestone.TextView) { isEditing = false; parent.completionController.dismiss() }
    }
}