import ByreAPI
import SwiftUI

typealias FindingState = Components.Schemas.FindingState
typealias FindingResponse = Components.Schemas.FindingResponse

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

@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 = "\(api.origin.absoluteString)/\(taskId)/\(n)/\(path)"
        if let cached = patches[key] {
            return try await cached.value
        }
        let fetched = Task<String?, any Error> {
            let ck = "\(api.origin.absoluteString)/\(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 }
}

func findingResponse(_ r: Review, _ index: Int) -> FindingResponse? {
    r.findingResponses.additionalProperties[String(index)]
}

func findingOpen(_ r: Review, _ index: Int) -> Bool {
    r.findingStates.additionalProperties[String(index)] == nil && findingResponse(r, index) == nil
}

func findingWhere(_ f: JSONDict) -> String {
    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
    return path.isEmpty ? "" : "\(path)\(line > 0 ? ":\(line)\(end > line ? "–\(end)" : "")" : "")"
}

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

    var body: some View {
        let f = findings(review)[index]
        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 = findingWhere(f)
        let md = MDContext(taskId: taskId)
        let response = findingResponse(review, index)
        VStack(alignment: .leading, spacing: 4) {
            HStack(alignment: .firstTextBaseline, spacing: 8) {
                Text("\(index + 1).")
                    .font(Fonts.font(11, weight: 700))
                    .foregroundStyle(Palette.muted)
                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)
                }
            }
            if let response {
                Text("agent \(response.response.rawValue): \(response.reason)")
                    .font(Fonts.font(11))
                    .foregroundStyle(Palette.muted)
                    .textSelection(.enabled)
                    .fixedSize(horizontal: false, vertical: true)
            }
            Group {
                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)
            }
            .opacity(response == nil ? 1 : 0.5)
        }
        .padding(.leading, 10)
        .overlay(alignment: .leading) {
            Rectangle().fill(Palette.border).frame(width: 1)
        }
    }
}

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)
    }
}

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

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

    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 = findings(review)[index]
        let whereText = findingWhere(f)
        let text = "Fix finding \(index + 1) 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 {
                try await store.messageTask(taskId, text)
            } catch {
                busy = false
                overlays.showAlert(errorText(error))
                return
            }
            do {
                try await mark(.fixed)
            } catch {
                busy = false
                overlays.showAlert("fix sent, but not recorded: \(errorText(error))")
            }
        }
    }

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