import SwiftUI
import WidgetKit

private struct ActivityEntry: TimelineEntry {
    let date: Date
    let serverName: String
    let rows: [ActivityRow]
    let message: String?
}

private struct PullsEntry: TimelineEntry {
    let date: Date
    let serverName: String
    let rows: [PullRow]
    let message: String?
}

private struct ActivityProvider: AppIntentTimelineProvider {
    func placeholder(in context: Context) -> ActivityEntry {
        ActivityEntry(
            date: .now,
            serverName: "My Server",
            rows: [
                ActivityRow(
                    icon: .push,
                    title: "Pushed to main in owner/project",
                    detail: "",
                    meta: "Just now",
                    target: .commit,
                    owner: "owner",
                    repository: "project",
                    number: 0,
                    sha: ""
                ),
                ActivityRow(
                    icon: .issue,
                    title: "Opened an issue in owner/project",
                    detail: "",
                    meta: "5m ago",
                    target: .issue,
                    owner: "owner",
                    repository: "project",
                    number: 1,
                    sha: ""
                ),
            ],
            message: nil
        )
    }

    func snapshot(for configuration: ActivityWidgetIntent, in context: Context) async -> ActivityEntry {
        context.isPreview ? placeholder(in: context) : await load(configuration)
    }

    func timeline(for configuration: ActivityWidgetIntent, in context: Context) async -> Timeline<ActivityEntry> {
        Timeline(
            entries: [await load(configuration)],
            policy: .after(Date.now.addingTimeInterval(15 * 60))
        )
    }

    private func load(_ configuration: ActivityWidgetIntent) async -> ActivityEntry {
        guard
            let selection = configuration.server,
            let server = WidgetEnvironment.server(for: selection)
        else {
            return ActivityEntry(
                date: .now,
                serverName: "Activity",
                rows: [],
                message: "Add a server in Gotcha, then configure this widget."
            )
        }
        do {
            let page = try await WidgetEnvironment.core().widgetActivity(serverId: server.id, limit: 6)
            return ActivityEntry(
                date: .now,
                serverName: page.serverName,
                rows: page.rows,
                message: page.rows.isEmpty ? "No recent activity." : nil
            )
        } catch {
            return ActivityEntry(
                date: .now,
                serverName: server.name,
                rows: [],
                message: error.localizedDescription
            )
        }
    }
}

private struct PullsProvider: AppIntentTimelineProvider {
    func placeholder(in context: Context) -> PullsEntry {
        PullsEntry(
            date: .now,
            serverName: "My Server",
            rows: [
                PullRow(
                    number: 42,
                    owner: "owner",
                    repository: "project",
                    state: .open,
                    title: "project  #42\nImprove the activity screen",
                    summary: "",
                    meta: "Open  ·  developer  ·  Just now"
                ),
                PullRow(
                    number: 41,
                    owner: "owner",
                    repository: "project",
                    state: .open,
                    title: "project  #41\nFix repository navigation",
                    summary: "",
                    meta: "Open  ·  developer  ·  10m ago"
                ),
            ],
            message: nil
        )
    }

    func snapshot(for configuration: PullsWidgetIntent, in context: Context) async -> PullsEntry {
        context.isPreview ? placeholder(in: context) : await load(configuration)
    }

    func timeline(for configuration: PullsWidgetIntent, in context: Context) async -> Timeline<PullsEntry> {
        Timeline(
            entries: [await load(configuration)],
            policy: .after(Date.now.addingTimeInterval(15 * 60))
        )
    }

    private func load(_ configuration: PullsWidgetIntent) async -> PullsEntry {
        guard
            let selection = configuration.server,
            let server = WidgetEnvironment.server(for: selection)
        else {
            return PullsEntry(
                date: .now,
                serverName: "Pull Requests",
                rows: [],
                message: "Add a server in Gotcha, then configure this widget."
            )
        }
        do {
            let page = try await WidgetEnvironment.core().widgetPulls(serverId: server.id, limit: 5)
            return PullsEntry(
                date: .now,
                serverName: page.serverName,
                rows: page.rows,
                message: page.rows.isEmpty ? "No open pull requests." : nil
            )
        } catch {
            return PullsEntry(
                date: .now,
                serverName: server.name,
                rows: [],
                message: error.localizedDescription
            )
        }
    }
}

private struct WidgetHeader: View {
    let title: String
    let symbol: String
    let server: String
    let updated: Date

    var body: some View {
        HStack(alignment: .firstTextBaseline) {
            Label(title, systemImage: symbol)
                .font(.headline)
            Spacer(minLength: 8)
            VStack(alignment: .trailing, spacing: 1) {
                Text(server)
                    .font(.caption.weight(.semibold))
                    .lineLimit(1)
                Text(updated, style: .relative)
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
        }
    }
}

private struct ActivityWidgetView: View {
    let entry: ActivityEntry

    var body: some View {
        VStack(alignment: .leading, spacing: 8) {
            WidgetHeader(
                title: "Activity",
                symbol: "waveform.path.ecg",
                server: entry.serverName,
                updated: entry.date
            )
            Divider()
            if let message = entry.message {
                emptyState(message, symbol: "clock.arrow.circlepath")
            } else {
                VStack(alignment: .leading, spacing: 7) {
                    ForEach(Array(entry.rows.enumerated()), id: \.offset) { _, row in
                        HStack(alignment: .firstTextBaseline, spacing: 8) {
                            Image(systemName: symbol(for: row.icon))
                                .foregroundStyle(.tint)
                                .frame(width: 16)
                            Text(row.title)
                                .font(.caption)
                                .lineLimit(1)
                            Spacer(minLength: 4)
                            Text(row.meta)
                                .font(.caption2)
                                .foregroundStyle(.secondary)
                                .lineLimit(1)
                        }
                        .accessibilityElement(children: .combine)
                    }
                }
                .privacySensitive()
            }
        }
        .containerBackground(.background, for: .widget)
        .widgetURL(URL(string: "gotcha://home"))
    }

    private func symbol(for icon: ActivityIcon) -> String {
        switch icon {
        case .repository: "shippingbox"
        case .issue: "exclamationmark.circle"
        case .pullRequest: "arrow.triangle.pull"
        case .branch: "arrow.triangle.branch"
        case .tag: "tag"
        case .push: "arrow.up.circle"
        case .release: "shippingbox.fill"
        }
    }
}

private struct PullsWidgetView: View {
    let entry: PullsEntry

    var body: some View {
        VStack(alignment: .leading, spacing: 8) {
            WidgetHeader(
                title: "Open Pull Requests",
                symbol: "arrow.triangle.pull",
                server: entry.serverName,
                updated: entry.date
            )
            Divider()
            if let message = entry.message {
                emptyState(message, symbol: "arrow.triangle.pull")
            } else {
                VStack(alignment: .leading, spacing: 8) {
                    ForEach(Array(entry.rows.enumerated()), id: \.offset) { _, row in
                        VStack(alignment: .leading, spacing: 2) {
                            Text(row.title)
                                .font(.caption.weight(.semibold))
                                .lineLimit(2)
                            Text(row.meta)
                                .font(.caption2)
                                .foregroundStyle(.secondary)
                                .lineLimit(1)
                        }
                        .accessibilityElement(children: .combine)
                    }
                }
                .privacySensitive()
            }
        }
        .containerBackground(.background, for: .widget)
        .widgetURL(URL(string: "gotcha://pulls"))
    }
}

private func emptyState(_ message: String, symbol: String) -> some View {
    VStack(spacing: 8) {
        Spacer()
        Image(systemName: symbol)
            .font(.title2)
            .foregroundStyle(.secondary)
        Text(message)
            .font(.caption)
            .foregroundStyle(.secondary)
            .multilineTextAlignment(.center)
        Spacer()
    }
    .frame(maxWidth: .infinity)
}

struct ActivityWidget: Widget {
    let kind = "GotchaActivityWidget"

    var body: some WidgetConfiguration {
        AppIntentConfiguration(kind: kind, intent: ActivityWidgetIntent.self, provider: ActivityProvider()) {
            ActivityWidgetView(entry: $0)
        }
        .configurationDisplayName("Recent Activity")
        .description("See the latest activity from a configured Gitea or Forgejo server.")
        .supportedFamilies([.systemLarge])
    }
}

struct PullsWidget: Widget {
    let kind = "GotchaPullsWidget"

    var body: some WidgetConfiguration {
        AppIntentConfiguration(kind: kind, intent: PullsWidgetIntent.self, provider: PullsProvider()) {
            PullsWidgetView(entry: $0)
        }
        .configurationDisplayName("Open Pull Requests")
        .description("See open pull requests from a configured Gitea or Forgejo server.")
        .supportedFamilies([.systemLarge])
    }
}

@main
struct GotchaWidgetBundle: WidgetBundle {
    var body: some Widget {
        ActivityWidget()
        PullsWidget()
    }
}