import ByreAPI
import SwiftUI

private enum Editing: Equatable {
    case none, new, existing(String)
}

struct WorkflowsView: View {
    @ViewState private var editing = Editing.none

    var body: some View {
        switch editing {
        case .none:
            list
        case .new:
            WorkflowEditor(original: nil) { editing = .none }
        case .existing(let name):
            WorkflowEditor(original: name) { editing = .none }
                .id(name)
        }
    }

    private var list: some View {
        ScrollView {
            VStack(alignment: .leading, spacing: 0) {
                HStack(alignment: .firstTextBaseline, spacing: 12) {
                    Text("Workflows run a brief through stages, each its own task. Run asks your lead to start one, so you can add the project and the brief first.")
                        .foregroundStyle(Palette.muted)
                        .fixedSize(horizontal: false, vertical: true)
                        .frame(maxWidth: .infinity, alignment: .leading)
                    Button("New") {
                        editing = .new
                    }
                    .buttonStyle(SmallLinkButtonStyle())
                    .help("Write a new workflow")
                }
                .padding(.top, 16)
                WorkflowList { editing = .existing($0) }
            }
            .padding(.horizontal, 16)
            .padding(.top, 8)
            .padding(.bottom, 16)
            .frame(maxWidth: .infinity, alignment: .leading)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(Palette.bg)
    }
}

private struct WorkflowList: View {
    let edit: (String) -> Void
    @Environment(Store.self) private var store
    @ViewState private var list: [WorkflowSummary]?
    @ViewState private var failure: String?
    @ViewState private var loads = 0
    @ViewState private var off: (() -> Void)?

    var body: some View {
        VStack(alignment: .leading, spacing: 0) {
            if let list {
                if list.isEmpty {
                    hint("No saved workflows. Ask your lead to write one.")
                } else {
                    ForEach(list.sorted { $0.name.localizedStandardCompare($1.name) == .orderedAscending }, id: \.name) { w in
                        WorkflowRow(workflow: w) { edit(w.name) }
                    }
                }
            } else if let failure {
                hint(failure)
            }
        }
        .padding(.top, 8)
        .onAppear {
            off = store.events.add { ev in
                if ev.kind == "workflow.updated" || ev.kind == "workflow.deleted" {
                    load()
                }
            }
            load()
        }
        .onDisappear {
            off?()
            off = nil
            loads += 1
        }
    }

    private func hint(_ text: String) -> some View {
        Text(text).foregroundStyle(Palette.muted)
    }

    private func load() {
        loads += 1
        let n = loads
        Task {
            do {
                let loaded = try await store.api.client.listWorkflows().ok.body.json
                if n == loads {
                    list = loaded
                }
            } catch {
                failure = errorText(error)
                list = nil
            }
        }
    }
}

private struct WorkflowRow: View {
    let workflow: WorkflowSummary
    let edit: () -> Void
    @Environment(Store.self) private var store
    @Environment(Overlays.self) private var overlays

    var body: some View {
        HStack(alignment: .firstTextBaseline, spacing: 12) {
            VStack(alignment: .leading, spacing: 2) {
                Text(workflow.name)
                    .font(Fonts.font(13, weight: 700))
                if !workflow.description.isEmpty {
                    Text(workflow.description)
                        .foregroundStyle(Palette.muted)
                }
            }
            .textSelection(.enabled)
            .frame(maxWidth: .infinity, alignment: .leading)
            .fixedSize(horizontal: false, vertical: true)
            Button("Edit") {
                edit()
            }
            .buttonStyle(SmallLinkButtonStyle())
            .help("See and change this workflow's steps and prompts")
            Button("Run") {
                run()
            }
            .buttonStyle(SmallLinkButtonStyle())
            .help("Open the Lead tab with a request to run this workflow in its composer")
            Button("Delete") {
                Task {
                    await delete()
                }
            }
            .buttonStyle(SmallLinkButtonStyle())
            .help("Delete this workflow; tasks already running it keep their copy")
        }
        .padding(.vertical, 6)
        .overlay(alignment: .top) {
            Rectangle().fill(Palette.border).frame(height: 1)
        }
    }

    private func delete() async {
        guard await overlays.showConfirm(["Delete the workflow \"\(workflow.name)\"?"], action: "Delete", danger: true) else {
            return
        }
        do {
            _ = try await store.api.client.deleteWorkflow(path: .init(name: workflow.name)).noContent
        } catch {
            overlays.showAlert(errorText(error))
        }
    }

    private func run() {
        let key = "message:lead"
        let ask = "Run the \"\(workflow.name)\" workflow: "
        let draft = store.drafts?.composerText(key) ?? ""
        store.drafts?.setComposerText(key, draft.isEmpty ? ask : "\(draft)\n\n\(ask)")
        overlays.leftTab = .lead
        overlays.leadFocus += 1
    }
}