import SwiftUI
import Foundation

struct FindInFileView: View {
    let content: String
    let onNavigate: (NSRange) -> Void
    @Environment(\.dismiss) var dismiss
    @State private var query = ""; @State private var isRegex = false; @State private var isCaseSensitive = false
    @State private var results: [Result] = []; @State private var selected = 0
    @FocusState private var focused: Bool

    struct Result: Identifiable {
        let id = UUID(); let range: NSRange; let lineNumber: Int; let lineText: String
    }

    var body: some View {
        NavigationStack {
            VStack(spacing: 0) {
                HStack(spacing: 8) {
                    Image(systemName: "magnifyingglass").foregroundStyle(.secondary)
                    TextField("Find…", text: $query).textFieldStyle(.plain).font(.system(.body, design: .monospaced))
                        .autocorrectionDisabled().autocapitalization(.none).focused($focused).onSubmit { navigateNext() }
                        .onChange(of: query) { _, _ in runSearch() }
                    if !results.isEmpty {
                        Text("\(selected+1)/\(results.count)").font(.system(.caption, design: .monospaced)).foregroundStyle(.secondary)
                        Button { navigatePrev() } label: { Image(systemName: "chevron.up") }.buttonStyle(.bordered).controlSize(.small)
                        Button { navigateNext() } label: { Image(systemName: "chevron.down") }.buttonStyle(.bordered).controlSize(.small)
                    }
                }
                .padding(.horizontal, 14).padding(.vertical, 10).background(Color(.secondarySystemBackground))
                Divider()
                if results.isEmpty {
                    ContentUnavailableView(query.isEmpty ? "Type to search" : "No Results", systemImage: "magnifyingglass")
                } else {
                    List(Array(results.enumerated()), id: \.element.id) { idx, r in
                        HStack(alignment: .top, spacing: 10) {
                            Text("\(r.lineNumber)").font(.system(.caption, design: .monospaced)).foregroundStyle(.secondary).frame(width: 36, alignment: .trailing)
                            Text(r.lineText).font(.system(.body, design: .monospaced)).lineLimit(1)
                        }
                        .background(idx == selected ? Color.accentColor.opacity(0.1) : .clear)
                        .onTapGesture { selected = idx; onNavigate(r.range); dismiss() }
                    }
                    .listStyle(.plain)
                }
            }
            .navigationTitle("Find in File").navigationBarTitleDisplayMode(.inline)
            .toolbar { ToolbarItem(placement: .cancellationAction) { Button("Done") { dismiss() } } }
            .onAppear { focused = true }
        }
        .presentationDetents([.medium, .large])
    }

    private func runSearch() {
        guard !query.isEmpty else { results = []; return }
        let lines = content.components(separatedBy: "\n")
        var found: [Result] = []; var offset = 0
        let pattern = isRegex ? query : NSRegularExpression.escapedPattern(for: query)
        let options: NSRegularExpression.Options = isCaseSensitive ? [] : .caseInsensitive
        guard let regex = try? NSRegularExpression(pattern: pattern, options: options) else { results = []; return }
        for (i, line) in lines.enumerated() {
            let r = NSRange(line.startIndex..., in: line)
            for m in regex.matches(in: line, range: r) {
                found.append(Result(range: NSRange(location: offset + m.range.location, length: m.range.length),
                                    lineNumber: i + 1, lineText: line.trimmingCharacters(in: .whitespaces)))
            }
            offset += line.count + 1
        }
        results = found; if !found.isEmpty { selected = 0; onNavigate(found[0].range) }
    }

    private func navigateNext() { guard !results.isEmpty else { return }; selected = (selected+1) % results.count; onNavigate(results[selected].range) }
    private func navigatePrev() { guard !results.isEmpty else { return }; selected = (selected-1+results.count) % results.count; onNavigate(results[selected].range) }
}