import ByreAPI
import SwiftUI

typealias FindingState = Components.Schemas.FindingState

private let findingHead = Re(#"^@@ -\d+(?:,\d+)? \+(\d+)(?:,\d+)? @@"#)

private func stateText(_ r: Review) -> String {
    switch r.state {
    case .running: "reviewing on \(r.vendor) (\(r.model))…"
    case .done: reviewCounts(r)
    case .failed: "failed"
    case .skipped: "skipped: no changes"
    }
}

@MainActor
private enum SnapshotPatches {
    static var changes: [String: Task<TaskChanges, any Error>] = [:]
    static var patches: [String: Task<String?, any Error>] = [:]

    static func patch(_ api: API, _ taskId: String, _ n: Int, _ path: String) async throws -> String? {
        let key = "\(taskId)/\(n)/\(path)"
        if let cached = patches[key] {
            return try await cached.value
        }
        let fetched = Task<String?, any Error> {
            let ck = "\(taskId)/\(n)"
            let pending = changes[ck] ?? Task {
                try await api.client.getTaskChanges(path: .init(taskId: taskId), query: .init(snapshot: n)).ok.body.json
            }
            changes[ck] = pending
            let c: TaskChanges
            do {
                c = try await pending.value
            } catch {
                changes[ck] = nil
                throw error
            }
            guard let f = c.files.first(where: { $0.path == path }), !f.binary else {
                return nil
            }
            return try await api.client.getTaskDiff(path: .init(taskId: taskId), query: .init(base: c.base, tree: c.tree, path: f.path, oldPath: f.oldPath)).ok.body.json.patch
        }
        patches[key] = fetched
        do {
            return try await fetched.value
        } catch {
            patches[key] = nil
            throw error
        }
    }
}

private func linesAround(_ patch: String, _ line: Int, _ end: Int) -> [(kind: PatchLine, text: String, at: Int)] {
    var lines: [(kind: PatchLine, text: String, at: Int)] = []
    var n = 0
    var inHunk = false
    for l in patch.components(separatedBy: "\n") {
        if let m = findingHead.exec(l) {
            n = Int(m[1]!) ?? 0
            inHunk = true
            continue
        }
        if !inHunk {
            continue
        }
        if l.hasPrefix("+") {
            lines.append((.add, l, n))
            n += 1
        } else if l.hasPrefix("-") {
            lines.append((.del, l, n))
        } else if l.hasPrefix(" ") {
            lines.append((.ctx, l, n))
            n += 1
        }
    }
    return lines.filter { $0.at >= line - 3 && $0.at <= end + 3 }
}

struct ReviewsView: View {
    @Environment(Store.self) private var store
    @ViewState private var reviews: [Review]?
    @ViewState private var error = ""
    @ViewState private var target = 0

    var body: some View {
        VStack(spacing: 0) {
            content
        }
        .frame(maxHeight: .infinity, alignment: .top)
        .task(id: store.selectedTaskId) {
            target += 1
            reviews = nil
            error = ""
            await load()
            let off = store.selectedFeed?.appended.add { events in
                if events.contains(where: isReviewEvent) {
                    Task {
                        await load()
                    }
                }
            }
            await untilCancelled()
            off?()
            target += 1
        }
    }

    private func load() async {
        guard let taskId = store.selectedTaskId else {
            return
        }
        target += 1
        let started = target
        do {
            let fresh = try await store.api.client.listReviews(path: .init(taskId: taskId)).ok.body.json
            if started == target {
                reviews = fresh
                error = ""
            }
        } catch {
            if started == target {
                reviews = nil
                self.error = errorText(error)
            }
        }
    }

    @ViewBuilder
    private var content: some View {
        if let taskId = store.selectedTaskId {
            if !error.isEmpty {
                EmptyText(text: error, error: true)
            } else if let reviews {
                if let lastReview = reviews.last {
                    let n = store.reviewed ?? lastReview.snapshotN
                    let shown = reviews.last { $0.snapshotN == n }
                    let ns = Array(Set([n] + reviews.map(\.snapshotN))).sorted(by: >)
                    let next = ns.filter { $0 > n }.last
                    let prev = ns.first { $0 < n }
                    HStack(spacing: 8) {
                        Picker("", selection: Binding(get: { n }, set: { store.pickReview($0) })) {
                            ForEach(ns, id: \.self) { s in
                                Text("snapshot #\(s)").tag(s)
                            }
                        }
                        .labelsHidden()
                        .pickerStyle(.menu)
                        .fixedSize()
                        .help("Snapshot whose review to show")
                        step(prev ?? n - 1, "← #\(prev ?? n - 1)", ns)
                        step(next ?? n + 1, "#\(next ?? n + 1) →", ns)
                    }
                    .modifier(HeaderBar())
                    ScrollView {
                        VStack(alignment: .leading, spacing: 12) {
                            if let shown {
                                ReviewCard(review: shown, taskId: taskId)
                                    .id(shown.id)
                            } else {
                                Muted(text: "No review of snapshot #\(n) yet.")
                            }
                        }
                        .padding(.horizontal, 16)
                        .padding(.top, 8)
                        .padding(.bottom, 16)
                    }
                } else {
                    EmptyText(text: "No reviews yet. Each new snapshot of the task is reviewed by an agent from the other vendor.")
                }
            } else {
                EmptyText(text: "Loading…")
            }
        } else {
            EmptyText(text: "No task selected.")
        }
    }

    private func step(_ to: Int, _ label: String, _ ns: [Int]) -> some View {
        Button(label) {
            store.pickReview(to)
        }
        .buttonStyle(SmallLinkButtonStyle(color: Palette.text))
        .disabled(!ns.contains(to))
    }
}

struct ReviewCard: View {
    let review: Review
    let taskId: String?

    var body: some View {
        VStack(alignment: .leading, spacing: 6) {
            HStack(alignment: .firstTextBaseline, spacing: 10) {
                Text("snapshot #\(review.snapshotN)")
                    .font(Fonts.font(11, weight: 700))
                    .foregroundStyle(Palette.text)
                Text(stateText(review))
                    .foregroundStyle(review.state == .failed ? Palette.warn : Palette.muted)
                Spacer(minLength: 0)
                Text(ago(review.createdAt))
                    .help(isoText(review.createdAt))
                if review.state == .running {
                    StopReviewButton(reviewId: review.id)
                }
            }
            .font(Fonts.font(11))
            .foregroundStyle(Palette.muted)
            if review.state == .failed {
                Text(review.error)
                    .foregroundStyle(Palette.danger)
                    .textSelection(.enabled)
            }
            if review.state == .done {
                ReviewResult(review: review, taskId: taskId)
            }
        }
        .padding(.horizontal, 14)
        .padding(.vertical, 10)
        .frame(maxWidth: .infinity, alignment: .leading)
        .background(Palette.raised, in: RoundedRectangle(cornerRadius: 10))
        .overlay(RoundedRectangle(cornerRadius: 10).stroke(Palette.border))
    }
}

private struct StopReviewButton: View {
    let reviewId: String
    @Environment(Store.self) private var store
    @Environment(Overlays.self) private var overlays
    @ViewState private var busy = false

    var body: some View {
        Button("Stop") {
            busy = true
            Task {
                do {
                    _ = try await store.api.client.stopReview(path: .init(reviewId: reviewId)).ok
                } catch {
                    busy = false
                    overlays.showAlert(errorText(error))
                }
            }
        }
        .buttonStyle(WebButtonStyle(danger: true))
        .disabled(busy)
        .help("End the reviewer and record this review as failed")
    }
}

private struct ReviewResult: View {
    let review: Review
    let taskId: String?

    var body: some View {
        let res = review.result?.value ?? [:]
        let fs = findings(review)
        let md = MDContext(taskId: taskId)
        VStack(alignment: .leading, spacing: 8) {
            MarkdownView(blocks: parseMarkdown(jsString(res["summary"] ?? "")), ctx: md)
            ReviewImages(value: res["images"] ?? nil)
            if !fs.isEmpty {
                VStack(alignment: .leading, spacing: 8) {
                    ForEach(Array(fs.enumerated()), id: \.offset) { i, f in
                        FindingRow(review: review, index: i, finding: f, taskId: taskId)
                    }
                }
            }
        }
    }
}

private struct FindingRow: View {
    let review: Review
    let index: Int
    let finding: JSONDict
    let taskId: String?

    var body: some View {
        let f = finding
        let severity = jsString(f["severity"] ?? "")
        let path = str(f, "path") ?? ""
        let line = max(0, int(f, "line") ?? 0)
        let endRaw = int(f, "end_line") ?? 0
        let end = endRaw > line ? endRaw : line
        let whereText = path.isEmpty ? "" : "\(path)\(line > 0 ? ":\(line)\(end > line ? "–\(end)" : "")" : "")"
        let md = MDContext(taskId: taskId)
        VStack(alignment: .leading, spacing: 4) {
            HStack(alignment: .firstTextBaseline, spacing: 8) {
                Text(severity)
                    .font(Fonts.font(11, weight: 700))
                    .foregroundStyle(severity == "critical" || severity == "high" ? Palette.danger : severity == "medium" ? Palette.warn : Palette.muted)
                if let category = str(f, "category"), !category.isEmpty {
                    Text(category).font(Fonts.font(11)).foregroundStyle(Palette.muted)
                }
                Text(jsString(f["title"] ?? ""))
                    .textSelection(.enabled)
                    .fixedSize(horizontal: false, vertical: true)
                if !whereText.isEmpty {
                    Text(whereText).font(Fonts.font(11)).foregroundStyle(Palette.muted).textSelection(.enabled)
                }
                Spacer(minLength: 0)
                if let taskId {
                    FindingActions(taskId: taskId, review: review, index: index, finding: f, whereText: whereText)
                }
            }
            if let taskId, !path.isEmpty, line > 0 {
                FindingDiff(taskId: taskId, n: review.snapshotN, path: path, line: line, end: end)
            }
            MarkdownView(blocks: parseMarkdown(jsString(f["detail"] ?? "")), ctx: md)
            ReviewImages(value: f["images"] ?? nil)
        }
        .padding(.top, 6)
        .overlay(alignment: .top) {
            Rectangle().fill(Palette.border).frame(height: 1)
        }
    }
}

private struct ReviewImages: View {
    let value: (any Sendable)?

    var body: some View {
        let imgs = (value as? [(any Sendable)?] ?? []).map { $0 as? JSONDict ?? [:] }
        if !imgs.isEmpty {
            FlowLayout(spacing: 10) {
                ForEach(Array(imgs.enumerated()), id: \.offset) { _, img in
                    let blob = jsString(img["blob"] ?? "")
                    let caption = str(img, "caption") ?? ""
                    VStack(alignment: .leading, spacing: 2) {
                        ByreImage(source: .blob(blob), src: "/api/blobs/\(blob)", maxHeight: 360)
                        if !caption.isEmpty {
                            Text(caption).font(Fonts.font(11)).foregroundStyle(Palette.muted)
                        }
                    }
                }
            }
            .padding(.vertical, 8)
        }
    }
}

private struct FindingDiff: View {
    let taskId: String
    let n: Int
    let path: String
    let line: Int
    let end: Int
    @Environment(Store.self) private var store
    @ViewState private var rows: [DiffRow]?
    @ViewState private var failure: String?

    var body: some View {
        Group {
            if let failure {
                Text("diff not available: \(failure)")
                    .font(Fonts.font(11))
                    .foregroundStyle(Palette.muted)
                    .padding(.horizontal, 10)
                    .padding(.vertical, 4)
                    .frame(maxWidth: .infinity, alignment: .leading)
                    .modifier(DiffBox())
            } else if let rows, !rows.isEmpty {
                DiffLines(rows: rows)
                    .modifier(DiffBox())
            }
        }
        .task(id: "\(taskId)/\(n)/\(path)/\(line)/\(end)") {
            failure = nil
            do {
                let patch = try await SnapshotPatches.patch(store.api, taskId, n, path)
                let lines = patch.map { linesAround($0, line, end) } ?? []
                var out: [DiffRow] = []
                for (i, d) in lines.enumerated() {
                    if i > 0 {
                        let prev = lines[i - 1]
                        if d.kind != .del && prev.kind != .del && d.at > prev.at + 1 {
                            out.append(DiffRow(text: "⋯", kind: .hunk))
                        }
                    }
                    let mark = d.kind != .del && d.at >= line && d.at <= end
                    out.append(DiffRow(text: d.text, kind: d.kind, lineno: d.kind == .del ? "" : String(d.at), mark: mark))
                }
                rows = out
            } catch {
                failure = errorText(error)
            }
        }
    }
}

private struct DiffBox: ViewModifier {
    func body(content: Content) -> some View {
        content
            .background(Palette.bg)
            .clipShape(RoundedRectangle(cornerRadius: 6))
            .overlay(RoundedRectangle(cornerRadius: 6).stroke(Palette.border))
            .padding(.top, 2)
    }
}

private struct FindingActions: View {
    let taskId: String
    let review: Review
    let index: Int
    let finding: JSONDict
    let whereText: String
    @Environment(Store.self) private var store
    @Environment(Overlays.self) private var overlays
    @ViewState private var done: FindingState?
    @ViewState private var busy = false

    var body: some View {
        if let s = done ?? review.findingStates.additionalProperties[String(index)] {
            Text(s == .fixed ? "fix sent" : "ignored")
                .font(Fonts.font(11))
                .foregroundStyle(Palette.muted)
        } else {
            HStack(spacing: 6) {
                Button("fix") {
                    fix()
                }
                .buttonStyle(SmallLinkButtonStyle())
                .help("Send this finding to the task's agent to fix")
                Button("ignore") {
                    ignore()
                }
                .buttonStyle(SmallLinkButtonStyle())
                .help("Mark this finding done without fixing it; Merge won't warn about it")
            }
            .disabled(busy)
        }
    }

    private func mark(_ s: FindingState) async throws {
        _ = try await store.api.client.setFindingState(path: .init(reviewId: review.id, index: index), body: .json(.init(state: s))).ok
    }

    private func fix() {
        let f = finding
        let text = "Fix this finding from the review of snapshot #\(review.snapshotN):\n\n**[\(jsString(f["severity"] ?? ""))] \(jsString(f["title"] ?? ""))**\(whereText.isEmpty ? "" : " (`\(whereText)`)")\n\n\(jsString(f["detail"] ?? ""))"
        busy = true
        Task {
            do {
                let sessions = try await store.api.client.listSessions(path: .init(taskId: taskId)).ok.body.json
                if let live = sessions.last(where: { $0.state != .completed }) {
                    _ = try await store.api.client.sendMessage(path: .init(sessionId: live.id), body: .json(.init(text: text))).accepted
                } else {
                    _ = try await store.api.client.createSession(path: .init(taskId: taskId), body: .json(.init(prompt: text))).created
                }
            } catch {
                busy = false
                overlays.showAlert(errorText(error))
                return
            }
            done = .fixed
            do {
                try await mark(.fixed)
            } catch {
                overlays.showAlert("fix sent, but not recorded: \(errorText(error))")
            }
        }
    }

    private func ignore() {
        busy = true
        Task {
            do {
                try await mark(.ignored)
                done = .ignored
            } catch {
                busy = false
                overlays.showAlert(errorText(error))
            }
        }
    }
}