//
//  AdminDashboardView.swift
//  FTStore Admin
//
//  The web dashboard's overview, folded onto a phone: KPI tiles, the two
//  30-day trends, ingestion per source, live transfers and the activity feed.
//

import SwiftUI
import Charts

struct AdminDashboardView: View {
	@EnvironmentObject private var session: AdminSession

	@StateObject private var _metrics = AdminLoader<AdminEnvelope<AdminMetricsOverview>>()
	@StateObject private var _status = AdminLoader<AdminEnvelope<AdminDashboardStatus>>()
	@StateObject private var _transfers = AdminLoader<AdminEnvelope<[AdminTransfer]>>()
	@StateObject private var _activity = AdminLoader<AdminActivityResponse>()

	private var _overview: AdminMetricsOverview? { _metrics.value?.data }

	var body: some View {
		List {
			_kpiSection
			_trendSection
			_sourceSection
			_transferSection
			_activitySection
		}
		.navigationTitle("Dashboard")
		.navigationBarTitleDisplayMode(.inline)
		.refreshable { await _reload() }
		.task { await _reload() }
	}

	// MARK: KPIs

	@ViewBuilder
	private var _kpiSection: some View {
		Section {
			if let overview = _overview {
				LazyVGrid(
					columns: [GridItem(.flexible(), spacing: 10), GridItem(.flexible(), spacing: 10)],
					spacing: 10
				) {
					AdminKPITile(
						title: "Builds",
						value: AdminFormat.count(overview.totalIpas),
						detail: "in the catalog",
						icon: "shippingbox.fill"
					)
					AdminKPITile(
						title: "Downloads",
						value: AdminFormat.count(overview.totalDownloads),
						detail: "all time",
						icon: "arrow.down.circle.fill"
					)
					AdminKPITile(
						title: "Success Rate",
						value: String(format: "%.1f%%", overview.successRate),
						detail: "pipeline",
						icon: "checkmark.seal.fill",
						tint: overview.successRate >= 90 ? .green : .orange
					)
					AdminKPITile(
						title: "Sources",
						value: AdminFormat.count(overview.activeChannels),
						detail: "active",
						icon: "antenna.radiowaves.left.and.right",
						tint: AdminTheme.brand
					)
				}
				.listRowInsets(EdgeInsets(top: 8, leading: 12, bottom: 8, trailing: 12))
				.listRowBackground(Color.clear)

				if let status = _status.value?.data {
					VStack(alignment: .leading, spacing: 4) {
						Text("Last scan \(AdminFormat.relative(status.lastScanAt))")
						Text("Last feed publish \(AdminFormat.relative(status.lastJsonGenAt))")
					}
					.font(.caption)
					.foregroundStyle(.secondary)
				}
			} else if let error = _metrics.errorMessage {
				AdminErrorRow(message: error) { Task { await _reload() } }
			} else {
				AdminLoadingRow()
			}
		}
	}

	// MARK: Trends

	@ViewBuilder
	private var _trendSection: some View {
		if let overview = _overview {
			Section("IPAs Added · 30 days") {
				_barChart(overview.ipasAddedByDay, tint: AdminTheme.brand)
			}

			Section("Downloads · 30 days") {
				_barChart(overview.releaseDownloadsByDay, tint: .green)
			}
		}
	}

	@ViewBuilder
	private func _barChart(_ points: [AdminMetricsOverview.DayPoint], tint: Color) -> some View {
		if points.isEmpty || points.allSatisfy({ $0.count == 0 }) {
			AdminEmptyRow(icon: "chart.bar", title: "No data yet")
		} else {
			Chart(points) { point in
				BarMark(
					x: .value("Day", point.date),
					y: .value("Count", point.count)
				)
				.foregroundStyle(tint)
			}
			// Dates are the raw `YYYY-MM-DD` keys the API sends; 30 of them
			// never fit on a phone, so the axis is dropped and the tallest bar
			// carries the scale.
			.chartXAxis(.hidden)
			.frame(height: 140)
			.padding(.vertical, 6)
		}
	}

	// MARK: Sources

	@ViewBuilder
	private var _sourceSection: some View {
		if let channels = _overview?.ipasByChannel, !channels.isEmpty {
			Section("Builds by Source") {
				ForEach(channels.sorted { $0.count > $1.count }) { entry in
					HStack {
						Text(entry.channel)
							.font(.subheadline)
							.lineLimit(1)
						Spacer()
						Text(AdminFormat.count(entry.count))
							.font(.subheadline.monospacedDigit())
							.foregroundStyle(.secondary)
					}
				}
			}
		}
	}

	// MARK: Transfers

	@ViewBuilder
	private var _transferSection: some View {
		if let transfers = _transfers.value?.data, !transfers.isEmpty {
			Section("In Flight") {
				ForEach(transfers) { transfer in
					VStack(alignment: .leading, spacing: 4) {
						Text(transfer.fileName ?? "Message \(transfer.messageId)")
							.font(.subheadline)
							.lineLimit(1)
						HStack(spacing: 8) {
							AdminStatusPill(status: transfer.status)
							Text(AdminFormat.bytes(transfer.fileSize))
								.font(.caption)
								.foregroundStyle(.secondary)
						}
					}
				}
			}
		}
	}

	// MARK: Activity

	@ViewBuilder
	private var _activitySection: some View {
		Section {
			if let entries = _activity.value?.data, !entries.isEmpty {
				ForEach(entries.prefix(15)) { entry in
					AdminActivityRow(entry: entry)
				}
			} else if _activity.isLoading {
				AdminLoadingRow()
			} else {
				AdminEmptyRow(icon: "clock", title: "No activity yet")
			}
		} header: {
			HStack {
				Text("Recent Activity")
				Spacer()
				NavigationLink("All Logs") { AdminLogsView() }
					.font(.caption)
			}
		}
	}

	// MARK: Loading

	private func _reload() async {
		async let metrics: Void = _metrics.load {
			try await session.get("/api/metrics/overview", as: AdminEnvelope<AdminMetricsOverview>.self)
		}
		async let status: Void = _status.load {
			try await session.get("/api/dashboard/status", as: AdminEnvelope<AdminDashboardStatus>.self)
		}
		async let transfers: Void = _transfers.load {
			try await session.get("/api/dashboard/transfers", as: AdminEnvelope<[AdminTransfer]>.self)
		}
		async let activity: Void = _activity.load {
			try await session.get(
				"/api/dashboard/activity",
				query: ["pageSize": "15"],
				as: AdminActivityResponse.self
			)
		}
		_ = await (metrics, status, transfers, activity)
	}
}

// MARK: - Shared row

struct AdminActivityRow: View {
	let entry: AdminActivityEntry

	var body: some View {
		VStack(alignment: .leading, spacing: 4) {
			Text(entry.message)
				.font(.subheadline)
				.lineLimit(3)
			HStack(spacing: 8) {
				AdminStatusPill(status: entry.status)
				Text(entry.type)
					.font(.caption2)
					.foregroundStyle(.tertiary)
				Spacer()
				Text(AdminFormat.relative(entry.createdAt))
					.font(.caption2)
					.foregroundStyle(.tertiary)
			}
		}
		.padding(.vertical, 2)
	}
}