import SwiftUI

struct WhatsNewFeature {
    let icon: String
    let color: Color
    let title: String
    let description: String
}

struct WhatsNewRelease: Identifiable {
    let version: String
    let features: [WhatsNewFeature]
    var id: String { version }
}

// MARK: - Versioned catalog
//
// One entry per released version, newest first. The sheet shows the CUMULATIVE
// diff between the version the user is coming from (lastSeenWhatsNewVersion)
// and the one they just installed — jumping 1.3.x → 1.4.2 shows 1.4.0 + 1.4.1
// + 1.4.2, not just the last step. ADD AN ENTRY HERE WITH EVERY RELEASE.
enum WhatsNewCatalog {
    static var releases: [WhatsNewRelease] {
        [
            WhatsNewRelease(version: "1.5.0", features: [
                WhatsNewFeature(
                    icon: "sparkles",
                    color: .appPrimary,
                    title: String(localized: "whats_new_150_redesign_title"),
                    description: String(localized: "whats_new_150_redesign_body")
                ),
                WhatsNewFeature(
                    icon: "figure.mind.and.body",
                    color: .positiveGreen,
                    title: String(localized: "whats_new_150_guided_title"),
                    description: String(localized: "whats_new_150_guided_body")
                ),
                WhatsNewFeature(
                    icon: "circle.dashed.inset.filled",
                    color: .orange,
                    title: String(localized: "whats_new_150_rings_title"),
                    description: String(localized: "whats_new_150_rings_body")
                )
            ]),
            WhatsNewRelease(version: "1.4.2", features: [
                WhatsNewFeature(
                    icon: "text.viewfinder",
                    color: .appPrimary,
                    title: String(localized: "whats_new_142_ocr_title"),
                    description: String(localized: "whats_new_142_ocr_body")
                ),
                WhatsNewFeature(
                    icon: "mic.fill",
                    color: .purple,
                    title: String(localized: "whats_new_142_siri_title"),
                    description: String(localized: "whats_new_142_siri_body")
                ),
                WhatsNewFeature(
                    icon: "chart.xyaxis.line",
                    color: .appSecondary,
                    title: String(localized: "whats_new_142_charts_title"),
                    description: String(localized: "whats_new_142_charts_body")
                )
            ]),
            WhatsNewRelease(version: "1.4.1", features: [
                WhatsNewFeature(
                    icon: "square.and.arrow.up.circle.fill",
                    color: .appPrimary,
                    title: String(localized: "whats_new_141_extension_title"),
                    description: String(localized: "whats_new_141_extension_body")
                ),
                WhatsNewFeature(
                    icon: "ipad.landscape",
                    color: .appSecondary,
                    title: String(localized: "whats_new_141_ipad_title"),
                    description: String(localized: "whats_new_141_ipad_body")
                ),
                WhatsNewFeature(
                    icon: "icloud.fill",
                    color: .cyan,
                    title: String(localized: "whats_new_141_icloud_title"),
                    description: String(localized: "whats_new_141_icloud_body")
                )
            ]),
            WhatsNewRelease(version: "1.4.0", features: [
                WhatsNewFeature(
                    icon: "bolt.circle.fill",
                    color: .appPrimary,
                    title: String(localized: "whats_new_quick_update_title"),
                    description: String(localized: "whats_new_quick_update_body")
                ),
                WhatsNewFeature(
                    icon: "flame.fill",
                    color: .orange,
                    title: String(localized: "whats_new_streak_title"),
                    description: String(localized: "whats_new_streak_body")
                ),
                WhatsNewFeature(
                    icon: "target",
                    color: .appSecondary,
                    title: String(localized: "whats_new_goals_title"),
                    description: String(localized: "whats_new_goals_body")
                )
            ])
        ]
    }

    /// Releases the user hasn't seen: newer than `since`, no newer than `current`.
    /// Newest first. `since` empty (pre-1.4.0 installs, before the key existed)
    /// is treated as "show everything in the catalog".
    static func pendingReleases(since: String, current: String) -> [WhatsNewRelease] {
        releases.filter { release in
            (since.isEmpty || compare(release.version, isNewerThan: since))
                && !compare(release.version, isNewerThan: current)
        }
    }

    /// Numeric semver-style comparison ("1.10.0" > "1.9.0").
    static func compare(_ a: String, isNewerThan b: String) -> Bool {
        let aParts = a.split(separator: ".").map { Int($0) ?? 0 }
        let bParts = b.split(separator: ".").map { Int($0) ?? 0 }
        for i in 0..<max(aParts.count, bParts.count) {
            let x = i < aParts.count ? aParts[i] : 0
            let y = i < bParts.count ? bParts[i] : 0
            if x != y { return x > y }
        }
        return false
    }
}

// MARK: - Sheet

struct WhatsNewView: View {
    let releases: [WhatsNewRelease]
    @Environment(\.dismiss) private var dismiss

    /// Version headers only add value when the user skipped several releases.
    private var showsVersionHeaders: Bool { releases.count > 1 }

    var body: some View {
        ZStack {
            AppBackground()

            VStack(spacing: 0) {
                VStack(spacing: 8) {
                    Text("🎉")
                        .font(.system(size: 48))
                    Text(String(format: String(localized: "whats_new_title_format"), releases.first?.version ?? ""))
                        .font(.title.weight(.bold))
                    Text(String(localized: "whats_new_subtitle"))
                        .font(.subheadline)
                        .foregroundColor(.secondary)
                        .multilineTextAlignment(.center)
                }
                .padding(.top, 32)
                .padding(.horizontal)

                ScrollView {
                    VStack(spacing: 16) {
                        ForEach(releases) { release in
                            VStack(alignment: .leading, spacing: 14) {
                                if showsVersionHeaders {
                                    Text(String(format: String(localized: "whats_new_version_header"), release.version))
                                        .font(.caption.weight(.bold))
                                        .foregroundColor(.appPrimary)
                                        .padding(.horizontal, 10)
                                        .padding(.vertical, 4)
                                        .background(Color.appPrimary.opacity(0.12))
                                        .clipShape(Capsule())
                                }
                                ForEach(release.features, id: \.title) { feature in
                                    HStack(spacing: 16) {
                                        Image(systemName: feature.icon)
                                            .font(.title2)
                                            .foregroundColor(feature.color)
                                            .frame(width: 40)
                                        VStack(alignment: .leading, spacing: 2) {
                                            Text(feature.title)
                                                .font(.subheadline.weight(.semibold))
                                            Text(feature.description)
                                                .font(.caption)
                                                .foregroundColor(.secondary)
                                        }
                                        Spacer()
                                    }
                                }
                            }
                            .padding()
                            .frame(maxWidth: .infinity, alignment: .leading)
                            .background(Color(.secondarySystemGroupedBackground))
                            .cornerRadius(16)
                        }
                    }
                    .padding()
                }

                Button {
                    dismiss()
                } label: {
                    Text(String(localized: "whats_new_continue"))
                        .font(.headline)
                        .foregroundColor(.white)
                        .frame(maxWidth: .infinity)
                        .padding()
                        .background(Color.appPrimary)
                        .cornerRadius(14)
                }
                .padding()
            }
        }
        .interactiveDismissDisabled()
    }
}