import ByreAPI
import SwiftUI

typealias AgentProcess = Components.Schemas.AgentProcess
typealias Zombie = Components.Schemas.Zombie

private let refreshKinds: Set<String> = ["session.created", "session.state", "task.created", "task.merged", "task.discarded", "project.created", "admin.health", "admin.clients"]

private let zombieLabel: [Zombie.KindPayload: String] = [
    .runningWithoutProcess: "Running with no process",
    .processWithoutSession: "Process with no session",
]

private func since(_ date: Date) -> String {
    let seconds = max(0, Int(Date().timeIntervalSince(date).rounded()))
    if seconds < 60 {
        return "\(seconds)s ago"
    }
    if seconds < 3600 {
        return "\(seconds / 60)m \(seconds % 60)s ago"
    }
    return ago(date)
}

private func bytes(_ n: Int64) -> String {
    let units = ["B", "KB", "MB", "GB", "TB"]
    var i = 0
    var v = Double(n)
    while v >= 1024 && i < units.count - 1 {
        v /= 1024
        i += 1
    }
    return "\(v.formatted(.number.precision(.fractionLength(i == 0 ? 0 : 1)).grouping(.never))) \(units[i])"
}

private func resetText(_ unixSeconds: Double) -> String {
    let at = Date(timeIntervalSince1970: unixSeconds)
    let time = at.formatted(Date.FormatStyle().weekday(.abbreviated).hour().minute())
    let minutes = Int((at.timeIntervalSinceNow / 60).rounded())
    if minutes <= 0 {
        return "\(time) (passed)"
    }
    let rel = minutes < 60 ? "\(minutes)m" : minutes < 1440 ? "\(minutes / 60)h \(minutes % 60)m" : "\(minutes / 1440)d \((minutes % 1440) / 60)h"
    return "\(time) (in \(rel))"
}

private func number(_ v: (any Sendable)??) -> Double? {
    switch v {
    case .some(.some(let x)):
        if let d = x as? Double {
            return d
        }
        if let i = x as? Int {
            return Double(i)
        }
        return nil
    default:
        return nil
    }
}

struct StatusView: View {
    @Environment(Store.self) private var store
    @ViewState private var status: ServerStatus?
    @ViewState private var error = ""
    @ViewState private var inFlight = false
    @ViewState private var again = false
    @ViewState private var off: (() -> Void)?

    var body: some View {
        Group {
            if let status {
                ScrollView {
                    VStack(alignment: .leading, spacing: 0) {
                        if !error.isEmpty {
                            Text(error).foregroundStyle(Palette.danger).padding(.top, 8)
                        }
                        Problems(status: status)
                        section("Running turns")
                        TurnList(status: status)
                        section("Rate limits")
                        let vendors = status.rateLimits.additionalProperties.keys.sorted()
                        VStack(alignment: .leading, spacing: 8) {
                            ForEach(vendors, id: \.self) { v in
                                RateLimitCard(vendor: v, info: status.rateLimits.additionalProperties[v]!.value)
                            }
                        }
                        if vendors.isEmpty {
                            Text("No vendor has reported a rate-limit status since byre started.").foregroundStyle(Palette.muted)
                        }
                        section("Clients")
                        ClientTable(status: status)
                        section("Server")
                        ServerRows(status: status)
                    }
                    .padding(.horizontal, 16)
                    .padding(.top, 8)
                    .padding(.bottom, 16)
                    .frame(maxWidth: .infinity, alignment: .leading)
                }
            } else {
                EmptyText(text: error.isEmpty ? "Loading…" : error, error: !error.isEmpty)
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(Palette.bg)
        .onAppear {
            off = store.events.add { ev in
                event(ev)
            }
            refresh()
        }
        .onDisappear {
            off?()
            off = nil
        }
        .onChange(of: store.connected) {
            if store.connected {
                refresh()
            }
        }
    }

    private func section(_ title: String) -> some View {
        Text(title)
            .font(Fonts.font(13, weight: 700))
            .padding(.top, 16)
            .padding(.bottom, 8)
    }

    private func refresh() {
        if inFlight {
            again = true
            return
        }
        inFlight = true
        Task {
            do {
                status = try await store.api.client.getStatus().ok.body.json
                error = ""
            } catch {
                self.error = "Couldn't load status: \(errorText(error))"
            }
            inFlight = false
            if again {
                again = false
                refresh()
            }
        }
    }

    private func event(_ ev: ByreEvent) {
        if refreshKinds.contains(ev.kind) || (ev.kind == "agent.vendor" && ev.payload.value["type"] as? String == "rate_limit_event") {
            refresh()
            return
        }
        guard var s = status else {
            return
        }
        var changed = false
        if let i = s.agentProcesses.firstIndex(where: { $0.sessionId == ev.agentSessionId }), ev.createdAt.timeIntervalSince(s.agentProcesses[i].lastEventAt) >= 1 {
            s.agentProcesses[i].lastEventAt = ev.createdAt
            changed = true
        }
        if ev.seq > s.lastEventSeq {
            s.lastEventSeq = ev.seq
            changed = true
        }
        if changed {
            status = s
        }
    }
}

private struct TaskLinkText: View {
    let taskId: String
    @Environment(Store.self) private var store

    var body: some View {
        let task = store.findTask(taskId)
        let project = task.flatMap { t in store.projects.first { $0.id == t.projectId } }
        Button {
            store.focusTask(taskId)
        } label: {
            Text("\(project.map { "\($0.name) ▸ " } ?? "")\(task?.title ?? taskId)")
                .foregroundStyle(store.taskColor(taskId) ?? Palette.accent)
        }
        .buttonStyle(.plain)
    }
}

private struct Problems: View {
    let status: ServerStatus

    var body: some View {
        let pe = status.protocolErrors
        let vendors = pe.counts.additionalProperties.keys.sorted()
        if !status.zombies.isEmpty || !vendors.isEmpty {
            VStack(alignment: .leading, spacing: 4) {
                Text("Problems")
                    .font(Fonts.font(13, weight: 700))
                    .padding(.top, 16)
                    .padding(.bottom, 4)
                ForEach(Array(status.zombies.enumerated()), id: \.offset) { _, z in
                    HStack(alignment: .firstTextBaseline, spacing: 6) {
                        Text(zombieLabel[z.kind]!).foregroundStyle(Palette.danger)
                        if let taskId = z.taskId {
                            TaskLinkText(taskId: taskId)
                        }
                        Text(z.detail).foregroundStyle(Palette.muted).textSelection(.enabled)
                    }
                }
                ForEach(vendors, id: \.self) { v in
                    let n = pe.counts.additionalProperties[v] ?? 0
                    VStack(alignment: .leading, spacing: 2) {
                        Text("\(v): \(n) bad stream line\(n == 1 ? "" : "s")").foregroundStyle(Palette.danger)
                        if let latest = pe.recent.first(where: { $0.vendor == v }) {
                            DetailsBox(boxed: false) {
                                Text("latest \(since(latest.at)): \(latest.reason)").foregroundStyle(Palette.muted)
                            } content: {
                                PreBox(text: latest.raw + (latest.raw.utf8.count < latest.size ? "… (\(bytes(Int64(latest.size))))" : ""), maxHeight: 180, size: 11)
                                    .padding(.top, 4)
                            }
                        }
                    }
                }
            }
        }
    }
}

private struct TurnList: View {
    let status: ServerStatus
    @Environment(Store.self) private var store

    var body: some View {
        VStack(alignment: .leading, spacing: 0) {
            ForEach(status.runningTurns, id: \.sessionId) { t in
                let task = store.findTask(t.taskId)
                let project = task.flatMap { tk in store.projects.first { $0.id == tk.projectId } }
                let color = store.taskColor(t.taskId) ?? Palette.accent
                HoverRow {
                    store.focusTask(t.taskId)
                } content: {
                    StateDot(filled: Palette.ok).help("running")
                    HStack(spacing: 0) {
                        if let project {
                            Text("\(project.name) ▸ ").foregroundStyle(Palette.muted)
                        }
                        Text(task?.title ?? t.taskId).foregroundStyle(color)
                    }
                    .lineLimit(1)
                    .truncationMode(.tail)
                    .frame(maxWidth: .infinity, alignment: .leading)
                    if let p = status.agentProcesses.first(where: { $0.sessionId == t.sessionId }) {
                        Text(p.health == .ok ? since(p.lastEventAt) : "\(p.health.rawValue) · \(since(p.lastEventAt))")
                            .font(Fonts.font(11))
                            .foregroundStyle(p.health == .ok ? Palette.muted : Palette.danger)
                    }
                    Text(t.vendor).font(Fonts.font(11)).foregroundStyle(Palette.muted)
                }
            }
            if status.runningTurns.isEmpty {
                Text("No turns running.")
                    .foregroundStyle(Palette.muted)
                    .padding(.horizontal, 10)
                    .padding(.vertical, 6)
            }
        }
    }
}

private struct RateLimitCard: View {
    let vendor: String
    let info: JSONDict

    var body: some View {
        let statusText = info["status"].map { jsString($0) } ?? "unknown"
        let tone = statusText == "allowed" ? Palette.ok : statusText == "rejected" ? Palette.danger : Palette.warn
        let windows = dict(info, "unifiedWindows") ?? [:]
        let rest = info.filter { !["status", "rateLimitType", "resetsAt", "unifiedWindows"].contains($0.key) }.sorted { $0.key < $1.key }
        VStack(alignment: .leading, spacing: 8) {
            HStack(alignment: .firstTextBaseline, spacing: 10) {
                Text(vendor).font(Fonts.font(13, weight: 700)).foregroundStyle(Palette.text)
                Text(statusText).font(Fonts.font(11, weight: 700)).foregroundStyle(tone)
                if let type = info["rateLimitType"] {
                    Text(jsString(type))
                }
                Spacer(minLength: 0)
                if let resets = number(info["resetsAt"]) {
                    Text("resets \(resetText(resets))")
                }
            }
            .font(Fonts.font(11))
            .foregroundStyle(Palette.muted)
            if !windows.isEmpty {
                Grid(alignment: .leading, horizontalSpacing: 12, verticalSpacing: 2) {
                    GridRow {
                        ForEach(["Window", "Used", "Elapsed", "Pace", "Resets"], id: \.self) { h in
                            Text(h).font(Fonts.font(11)).foregroundStyle(Palette.muted)
                        }
                    }
                    Divider().overlay(Palette.border)
                    ForEach(windows.keys.sorted(), id: \.self) { name in
                        let w = dict(windows, name) ?? [:]
                        let used = number(w["utilization"])
                        let elapsed = elapsedFraction(w)
                        GridRow {
                            Text(name)
                            Text(used.map { "\(Int(($0 * 100).rounded()))%" } ?? "—")
                                .foregroundStyle(used.map { $0 >= 0.9 ? Palette.danger : $0 >= 0.7 ? Palette.warn : Palette.text } ?? Palette.text)
                            Text(elapsed.map { "\(Int(($0 * 100).rounded()))%" } ?? "—")
                            PaceBar(used: used, elapsed: elapsed)
                                .gridColumnAlignment(.leading)
                            Text(number(w["resetsAt"]).map(resetText) ?? "—")
                        }
                        Divider().overlay(Palette.border)
                    }
                }
            }
            if !rest.isEmpty {
                Grid(alignment: .leading, horizontalSpacing: 16, verticalSpacing: 2) {
                    ForEach(rest, id: \.key) { k, v in
                        GridRow {
                            Text(k).foregroundStyle(Palette.muted)
                            Text(v is JSONDict || v is [(any Sendable)?] ? compactJSONText(v) : jsString(v)).textSelection(.enabled)
                        }
                    }
                }
            }
        }
    }

    private func elapsedFraction(_ w: JSONDict) -> Double? {
        guard let resets = number(w["resetsAt"]), let mins = number(w["windowMins"]) else {
            return nil
        }
        let remaining = resets * 1000 - Date().timeIntervalSince1970 * 1000
        return min(1, max(0, 1 - remaining / (mins * 60000)))
    }
}

private func compactJSONText(_ v: (any Sendable)?) -> String {
    prettyJSON(v).components(separatedBy: "\n").map { trimmed($0) }.joined(separator: " ")
}

private struct PaceBar: View {
    let used: Double?
    let elapsed: Double?

    var body: some View {
        if let used, let elapsed {
            let diff = Int(((used - elapsed) * 100).rounded())
            let title = diff > 0 ? "\(diff) points ahead of an even pace" : diff < 0 ? "\(-diff) points behind an even pace" : "on an even pace"
            GeometryReader { g in
                ZStack(alignment: .leading) {
                    Rectangle()
                        .fill(Palette.raised)
                        .overlay((used > elapsed ? Palette.warn : Palette.ok).opacity(0.55))
                        .frame(width: g.size.width * min(1, used))
                    Rectangle()
                        .fill(Palette.text)
                        .frame(width: 2, height: g.size.height + 6)
                        .offset(x: g.size.width * elapsed - 1)
                }
            }
            .padding(1)
            .background {
                RoundedRectangle(cornerRadius: 2)
                    .fill(Palette.surface)
                    .overlay(RoundedRectangle(cornerRadius: 2).strokeBorder(Palette.border))
            }
            .frame(minWidth: 80, maxWidth: .infinity)
            .frame(height: 10)
            .help(title)
        } else {
            Text("—")
        }
    }
}

private struct ClientTable: View {
    let status: ServerStatus

    var body: some View {
        if status.clients.isEmpty {
            Text("No clients connected.").foregroundStyle(Palette.muted)
        } else {
            Grid(alignment: .leading, horizontalSpacing: 12, verticalSpacing: 2) {
                GridRow {
                    ForEach(["Mac", "User", "Build", "Connected", "Last action"], id: \.self) { h in
                        Text(h).font(Fonts.font(11)).foregroundStyle(Palette.muted)
                    }
                }
                Divider().overlay(Palette.border)
                ForEach(Array(status.clients.enumerated()), id: \.offset) { _, c in
                    GridRow {
                        Text(c.host.isEmpty ? "—" : c.host)
                        Text(c.login)
                        Text(c.commit.isEmpty ? "—" : String(c.commit.prefix(8))).help(c.commit)
                        Text(since(c.connectedAt))
                        Text(c.lastActionAt.map(since) ?? "—")
                    }
                    .textSelection(.enabled)
                    Divider().overlay(Palette.border)
                }
            }
        }
    }
}

private struct ServerRows: View {
    let status: ServerStatus

    var body: some View {
        let rows: [(String, String)] = [
            ("Started", "\(status.startedAt.formatted(date: .numeric, time: .standard)) (\(ago(status.startedAt)))"),
            ("Agent processes", String(status.liveAgents)),
            ("Projects", String(status.projects)),
            ("Active tasks", String(status.activeTasks)),
            ("Live clients", String(status.sseClients)),
            ("Database", bytes(status.dbBytes)),
            ("Last event", "#\(status.lastEventSeq)"),
        ]
        Grid(alignment: .leading, horizontalSpacing: 16, verticalSpacing: 2) {
            ForEach(rows, id: \.0) { k, v in
                GridRow {
                    Text(k).foregroundStyle(Palette.muted)
                    Text(v).textSelection(.enabled)
                }
            }
        }
        .padding(.top, 8)
    }
}