import SwiftUI

struct PullRequestStatusButton: View {
  let model: PullRequestStatusModel
  let codeHost: CodeHost
  @Environment(CommandKeyObserver.self) private var commandKeyObserver
  @Environment(\.resolvedKeybindings) private var resolvedKeybindings

  var body: some View {
    PullRequestChecksPopoverButton(pullRequest: model.pullRequest) {
      let breakdown = PullRequestCheckBreakdown(checks: model.statusChecks)
      let showsChecksRing = breakdown.total > 0 && model.state != "MERGED"
      HStack(spacing: 6) {
        PullRequestBadgeView(
          text: model.badgeText,
          color: model.badgeColor
        )
        .layoutPriority(1)
        if showsChecksRing {
          PullRequestChecksRingView(breakdown: breakdown)
        }
        if let detailText = model.detailText {
          Text(
            commandKeyObserver.isPressed
              ? openPullRequestLabel : detailText
          )
          .lineLimit(1)
        } else if commandKeyObserver.isPressed {
          Text(openPullRequestLabel)
            .lineLimit(1)
        }
        if model.detailText == nil, !commandKeyObserver.isPressed {
          Text(model.title)
            .lineLimit(1)
        }
      }
    }
    .font(.caption)
  }

  private var openPullRequestLabel: String {
    let base = String(localized: "Open on \(codeHost.displayName)")
    let shortcut = AppShortcuts.resolvedShortcut(
      for: AppShortcuts.CommandID.openPullRequest,
      in: resolvedKeybindings
    )?.display
    if let shortcut {
      return "\(base) \(shortcut)"
    }
    return base
  }
}

struct PullRequestStatusModel: Equatable {
  let pullRequest: GithubPullRequest
  let number: Int
  let state: String?
  let title: String
  let statusChecks: [GithubPullRequestStatusCheck]
  let detailText: String?

  init?(pullRequest: GithubPullRequest?) {
    guard
      let pullRequest,
      Self.shouldDisplay(state: pullRequest.state, number: pullRequest.number)
    else {
      return nil
    }
    self.pullRequest = pullRequest
    self.number = pullRequest.number
    let state = pullRequest.state.uppercased()
    self.state = state
    self.title = pullRequest.title
    if state == "MERGED" {
      self.detailText = nil
      self.statusChecks = []
      return
    }
    if state == "CLOSED" {
      self.detailText = nil
      self.statusChecks = []
      return
    }
    let isDraft = pullRequest.isDraft
    let prefix = isDraft ? "(Drafted) " : ""
    let mergeReadiness = PullRequestMergeReadiness(pullRequest: pullRequest)
    let checks = pullRequest.statusCheckRollup?.checks ?? []
    self.statusChecks = checks
    let checksDetail: String?
    if checks.isEmpty {
      checksDetail = nil
    } else {
      let breakdown = PullRequestCheckBreakdown(checks: checks)
      let checksLabel = breakdown.total == 1 ? "check" : "checks"
      checksDetail = breakdown.summaryText + " \(checksLabel)"
    }
    if mergeReadiness.isBlocking {
      if let checksDetail {
        self.detailText = prefix + mergeReadiness.label + " - " + checksDetail
      } else {
        self.detailText = prefix + mergeReadiness.label
      }
      return
    }
    if let checksDetail {
      self.detailText = prefix + checksDetail
    } else {
      self.detailText = isDraft ? "(Drafted)" : nil
    }
  }

  var badgeText: String {
    PullRequestBadgeStyle.style(state: state, number: number)?.text ?? "#\(number)"
  }

  var badgeColor: Color {
    PullRequestBadgeStyle.style(state: state, number: number)?.color ?? .secondary
  }

  static func shouldDisplay(state: String?, number: Int?) -> Bool {
    guard number != nil else {
      return false
    }
    let uppercasedState = state?.uppercased()
    return uppercasedState != nil && uppercasedState != "UNKNOWN"
  }
}