import SwiftUI

struct FeedView: View {
    @EnvironmentObject private var localization: LocalizationStore
    @EnvironmentObject private var analytics: HermesAnalyticsClient
    @EnvironmentObject private var repository: HermesRepository

    let onWatchPreview: () -> Void = {}
    let onRetry: () -> Void

    var body: some View {
        TimelineView(.periodic(from: Date(), by: 1)) { _ in
            let round = repository.currentRound
            let now = repository.serverNow()
            let bannerMessage = hermesUserFacingErrorMessage(
                localization: localization,
                localeCode: localization.localeCode,
                error: repository.errorCause
            )

            VStack(alignment: .leading, spacing: HermesTheme.sectionSpacing) {
                HermesSectionHeader(
                    title: localization.string(for: "feed.title"),
                    subtitle: localization.string(for: "feed.subtitle")
                )

                if round == nil {
                    if let bannerMessage {
                        feedErrorState(
                            message: bannerMessage,
                            retryText: localization.string(for: "common.retry"),
                            onRetry: onRetry
                        )
                    } else {
                        feedLoadingState(
                            title: localization.string(for: "common.loading"),
                            subtitle: localization.string(for: "feed.subtitle")
                        )
                    }
                } else {
                    if let bannerMessage {
                        feedBanner(message: bannerMessage)
                    }

                    heroCard(round: round)

                    HStack(spacing: 12) {
                        HermesMetricPill(
                            label: localization.string(for: "feed.lock_label"),
                            value: round.map { Self.countdownText(for: $0.event.lockAt.timeIntervalSince(now)) } ?? "--:--"
                        )
                        HermesMetricPill(
                            label: localization.string(for: "feed.odds_label"),
                            value: round.map { Self.formatOdds($0) } ?? "--"
                        )
                    }

                    Button {
                        analytics.track("next_round_requested", attributes: ["screen_name": "feed"])
                        analytics.track("cta_pressed", attributes: ["screen_name": "feed", "action": "watch_preview"])
                        onWatchPreview()
                    } label: {
                        Text(localization.string(for: "feed.cta"))
                    }
                    .buttonStyle(HermesPrimaryButtonStyle())
                    .disabled(round == nil)
                }
            }
            .onAppear {
                analytics.track("feed_viewed", attributes: ["screen_name": "feed"])
                analytics.track("screen_viewed", attributes: ["screen_name": "feed"])
            }
        }
        .hermesCard(elevated: true)
    }

    @ViewBuilder
    private func heroCard(round: HermesRound?) -> some View {
        ZStack(alignment: .bottomLeading) {
            RoundedRectangle(cornerRadius: HermesTheme.cornerRadius, style: .continuous)
                .fill(
                    LinearGradient(
                        colors: [HermesTheme.surfaceElevated, HermesTheme.background],
                        startPoint: .topLeading,
                        endPoint: .bottomTrailing
                    )
                )
                .frame(height: 220)

            VStack(alignment: .leading, spacing: 8) {
                Text(round.map { localizedEventTitle($0) } ?? localization.string(for: "feed.hero_title"))
                    .font(.title2.weight(.bold))
                    .foregroundStyle(HermesTheme.textPrimary)

                Text(localization.string(for: "feed.hero_subtitle"))
                    .font(.callout)
                    .foregroundStyle(HermesTheme.textSecondary)
                    .frame(maxWidth: 260, alignment: .leading)
            }
            .padding(HermesTheme.contentPadding)
        }
    }

    @ViewBuilder
    private func feedLoadingState(title: String, subtitle: String) -> some View {
        VStack(alignment: .leading, spacing: 8) {
            Text(title)
                .font(.title2.weight(.bold))
                .foregroundStyle(HermesTheme.textPrimary)
            Text(subtitle)
                .font(.callout)
                .foregroundStyle(HermesTheme.textSecondary)
        }
        .padding(HermesTheme.contentPadding)
        .frame(maxWidth: .infinity, minHeight: 220, alignment: .center)
        .background(
            RoundedRectangle(cornerRadius: HermesTheme.cornerRadius, style: .continuous)
                .fill(
                    LinearGradient(
                        colors: [HermesTheme.surfaceElevated, HermesTheme.background],
                        startPoint: .topLeading,
                        endPoint: .bottomTrailing
                    )
                )
        )
    }

    @ViewBuilder
    private func feedErrorState(message: String, retryText: String, onRetry: @escaping () -> Void) -> some View {
        VStack(alignment: .leading, spacing: 12) {
            Text(message)
                .font(.callout)
                .foregroundStyle(HermesTheme.warning)

            Button {
                onRetry()
            } label: {
                Text(retryText)
            }
            .buttonStyle(HermesSecondaryButtonStyle())
        }
    }

    @ViewBuilder
    private func feedBanner(message: String) -> some View {
        Text(message)
            .font(.callout)
            .foregroundStyle(HermesTheme.warning)
            .padding(.horizontal, 12)
            .padding(.vertical, 10)
            .frame(maxWidth: .infinity, alignment: .leading)
            .background(HermesTheme.warning.opacity(0.12))
            .clipShape(RoundedRectangle(cornerRadius: HermesTheme.insetRadius, style: .continuous))
    }

    private func localizedEventTitle(_ round: HermesRound) -> String {
        localization.localeCode == "sv" ? round.event.titleSv : round.event.titleEn
    }

    private static func countdownText(for remaining: TimeInterval) -> String {
        let totalSeconds = max(Int(remaining.rounded(.down)), 0)
        let minutes = totalSeconds / 60
        let seconds = totalSeconds % 60
        return String(format: "%02d:%02d", minutes, seconds)
    }

    private static func formatOdds(_ round: HermesRound) -> String {
        let oddsByOutcomeId = Dictionary(uniqueKeysWithValues: round.oddsVersion.odds.map { ($0.outcomeId, $0) })
        return round.market.outcomes
            .sorted(by: { $0.sortOrder < $1.sortOrder })
            .compactMap { oddsByOutcomeId[$0.id]?.decimalOdds }
            .map { String(format: "%.2f", $0) }
            .joined(separator: " / ")
    }
}