import SwiftUI

struct ContentView: View {
	@ObservedObject var viewModel: ImportFlowViewModel

	var body: some View {
		NavigationStack {
			List {
				NavigationLink {
					SegmentImportView(viewModel: viewModel)
				} label: {
					VStack(alignment: .leading, spacing: 4) {
						Text(viewModel.template.localizedHealthTypeName)
							.font(.headline)
						Text(String(localized: "label.template"))
							.font(.caption)
							.foregroundStyle(.secondary)
					}
				}
			}
			.navigationTitle(String(localized: "screen.title.segments"))
		}
	}
}

private struct SegmentImportView: View {
	@ObservedObject var viewModel: ImportFlowViewModel
	@State private var showingFileImporter = false
	@State private var fieldStates: [String: ImportFlowViewModel.FieldMappingState] = [:]

	var body: some View {
		Form {
			sourceSection
			fieldsSection
			testImportSection
		}
		.navigationTitle(viewModel.template.localizedHealthTypeName)
		.navigationBarTitleDisplayMode(.inline)
		.fileImporter(
			isPresented: $showingFileImporter,
			allowedContentTypes: viewModel.supportedContentTypes,
			allowsMultipleSelection: false
		) { result in
			switch result {
			case let .success(urls):
				if let url = urls.first {
					viewModel.loadFile(from: url)
				}
			case let .failure(error):
				viewModel.errorMessage = error.localizedDescription
			}
		}
		.alert(String(localized: "error.title"), isPresented: Binding(
			get: { viewModel.errorMessage != nil },
			set: { isVisible in
				if !isVisible {
					viewModel.errorMessage = nil
				}
			}
		), actions: {
			Button(String(localized: "button.ok"), role: .cancel) {}
		}, message: {
			Text(viewModel.errorMessage ?? "")
		})
		.onAppear {
			refreshFieldStates()
		}
		.onChange(of: viewModel.entries.count) { _, _ in
			refreshFieldStates()
		}
		.onChange(of: viewModel.mapping) { _, _ in
			refreshFieldStates()
		}
		.onChange(of: viewModel.fieldFormatters) { _, _ in
			refreshFieldStates()
		}
		.onChange(of: viewModel.moodValenceScale) { _, _ in
			refreshFieldStates()
		}
	}

	private var sourceSection: some View {
		Section(String(localized: "section.source")) {
			Button(String(localized: "button.load_json")) {
				showingFileImporter = true
			}
			Button(String(localized: "button.load_sample")) {
				viewModel.loadBundledSample()
			}
			Text(String.localizedStringWithFormat(
				NSLocalizedString("label.records_loaded", comment: ""),
				viewModel.entries.count
			))
			if !viewModel.statusMessage.isEmpty {
				Text(viewModel.statusMessage)
					.font(.caption)
					.foregroundStyle(.secondary)
			}
		}
	}

	private var fieldsSection: some View {
		Section(String(localized: "section.mapping")) {
			ForEach(viewModel.template.fields) { field in
				NavigationLink {
					FieldMappingDetailView(viewModel: viewModel, field: field)
				} label: {
					HStack {
						VStack(alignment: .leading, spacing: 4) {
							Text(field.title)
							Text(field.targetFormat)
								.font(.caption2)
								.foregroundStyle(.secondary)
						}
						Spacer()
						Text(fieldStateText(fieldStates[field.id] ?? .incomplete))
							.font(.caption2)
							.foregroundStyle(color(for: fieldStates[field.id] ?? .incomplete))
					}
				}
			}
		}
	}

	private var testImportSection: some View {
		Section(String(localized: "section.commit")) {
			Button(String(localized: "button.run_dry_run")) {
				viewModel.runDryRun()
			}

			if let result = viewModel.dryRunResult {
				Text(String.localizedStringWithFormat(
					NSLocalizedString("label.preview_count", comment: ""),
					result.drafts.count
				))
				if !result.errors.isEmpty {
					Text(String.localizedStringWithFormat(
						NSLocalizedString("label.errors_count", comment: ""),
						result.errors.count
					))
					.foregroundStyle(.red)
				}
				if !result.warnings.isEmpty {
					Text(String.localizedStringWithFormat(
						NSLocalizedString("label.warnings_count", comment: ""),
						result.warnings.count
					))
					.foregroundStyle(.orange)
				}
			}

			Button {
				Task {
					await viewModel.commitImport()
				}
			} label: {
				if viewModel.isImporting {
					ProgressView()
				} else {
					Text(String(localized: "button.commit"))
				}
			}
			.disabled(viewModel.isImporting)

			Text(String(localized: "text.commit_notice"))
				.font(.caption)
				.foregroundStyle(.secondary)
		}
	}

	private func color(for state: ImportFlowViewModel.FieldMappingState) -> Color {
		switch state {
		case .incomplete:
			return .secondary
		case .partiallyValid:
			return .yellow
		case .valid:
			return .green
		}
	}

	private func fieldStateText(_ state: ImportFlowViewModel.FieldMappingState) -> String {
		switch state {
		case .incomplete:
			return String(localized: "state.incomplete")
		case .partiallyValid:
			return String(localized: "state.partial")
		case .valid:
			return String(localized: "state.valid")
		}
	}

	private func refreshFieldStates() {
		var next: [String: ImportFlowViewModel.FieldMappingState] = [:]
		for field in viewModel.template.fields {
			next[field.id] = viewModel.fieldState(for: field)
		}
		fieldStates = next
	}
}