import Foundation

protocol MailServicing {
    func loadThreads() async throws -> [MailThread]
    func send(draft: ComposeDraft) async throws -> MailThread
}

struct MockMailService: MailServicing {
    private let me = MailPerson(name: "Phil Kunz", email: "phil@social.io")

    func loadThreads() async throws -> [MailThread] {
        try await Task.sleep(for: .milliseconds(150))
        return seededThreads.sorted { $0.lastUpdated > $1.lastUpdated }
    }

    func send(draft: ComposeDraft) async throws -> MailThread {
        try await Task.sleep(for: .milliseconds(120))

        let threadRouteID = "sent-\(UUID().uuidString.lowercased())"
        let messageRouteID = "\(threadRouteID)-message"

        let recipientNames = draft.to
            .split(separator: ",")
            .map { $0.trimmingCharacters(in: .whitespacesAndNewlines) }
            .filter { !$0.isEmpty }

        let recipients = recipientNames.map { raw in
            MailPerson(
                name: raw.components(separatedBy: "@").first?.capitalized ?? raw,
                email: raw
            )
        }

        let message = MailMessage(
            routeID: messageRouteID,
            sender: me,
            recipients: recipients,
            sentAt: .now,
            body: draft.body
        )

        return MailThread(
            routeID: threadRouteID,
            mailbox: .sent,
            subject: draft.subject.isEmpty ? "(No Subject)" : draft.subject,
            participants: recipients + [me],
            messages: [message],
            isUnread: false,
            isStarred: false,
            tags: ["Sent"]
        )
    }

    private var seededThreads: [MailThread] {
        let alex = MailPerson(name: "Alex Rivera", email: "alex@social.io")
        let nora = MailPerson(name: "Nora Chen", email: "nora@social.io")
        let tanya = MailPerson(name: "Tanya Hall", email: "tanya@design.social.io")
        let ops = MailPerson(name: "Ops Bot", email: "ops@social.io")
        let investor = MailPerson(name: "Mina Park", email: "mina@northshore.vc")

        return [
            MailThread(
                routeID: "launch-copy",
                mailbox: .inbox,
                subject: "Launch copy for the onboarding flow",
                participants: [tanya, me],
                messages: [
                    MailMessage(
                        routeID: "launch-copy-1",
                        sender: tanya,
                        recipients: [me],
                        sentAt: .now.addingTimeInterval(-3600 * 2),
                        body: "I tightened the onboarding copy and added a warmer empty-state tone. If you're good with it, I can hand the strings to the app team today."
                    ),
                    MailMessage(
                        routeID: "launch-copy-2",
                        sender: me,
                        recipients: [tanya],
                        sentAt: .now.addingTimeInterval(-3600),
                        body: "Looks strong. Let's keep the playful language on iPhone and simplify the desktop first-run copy a bit."
                    )
                ],
                isUnread: true,
                isStarred: true,
                tags: ["Design", "Launch"]
            ),
            MailThread(
                routeID: "daily-sync-status",
                mailbox: .inbox,
                subject: "Daily inbox sync status",
                participants: [ops, me],
                messages: [
                    MailMessage(
                        routeID: "daily-sync-status-1",
                        sender: ops,
                        recipients: [me],
                        sentAt: .now.addingTimeInterval(-3600 * 4),
                        body: "Mock sync complete. 1,284 messages mirrored from staging. Attachment fetch remains disabled in the sandbox profile."
                    )
                ],
                isUnread: false,
                isStarred: false,
                tags: ["System"]
            ),
            MailThread(
                routeID: "investor-update",
                mailbox: .inbox,
                subject: "Investor update before next Friday",
                participants: [investor, me],
                messages: [
                    MailMessage(
                        routeID: "investor-update-1",
                        sender: investor,
                        recipients: [me],
                        sentAt: .now.addingTimeInterval(-3600 * 26),
                        body: "Could you send a concise product update and a few screenshots of the new mail experience before Friday? Interested in how you are differentiating from commodity inboxes."
                    )
                ],
                isUnread: true,
                isStarred: false,
                tags: ["External"]
            ),
            MailThread(
                routeID: "search-ranking-polish",
                mailbox: .sent,
                subject: "Re: Search ranking polish",
                participants: [alex, me],
                messages: [
                    MailMessage(
                        routeID: "search-ranking-polish-1",
                        sender: alex,
                        recipients: [me],
                        sentAt: .now.addingTimeInterval(-3600 * 30),
                        body: "The current search sort is useful, but I still feel too much recency over intent."
                    ),
                    MailMessage(
                        routeID: "search-ranking-polish-2",
                        sender: me,
                        recipients: [alex],
                        sentAt: .now.addingTimeInterval(-3600 * 28),
                        body: "Agreed. I want us to bias toward active collaborators and threads with lightweight action language like review, approve, or ship."
                    )
                ],
                isUnread: false,
                isStarred: false,
                tags: ["Search"]
            ),
            MailThread(
                routeID: "welcome-to-socialio",
                mailbox: .drafts,
                subject: "Welcome to social.io mail",
                participants: [me, nora],
                messages: [
                    MailMessage(
                        routeID: "welcome-to-socialio-1",
                        sender: me,
                        recipients: [nora],
                        sentAt: .now.addingTimeInterval(-3600 * 6),
                        body: "Thanks for joining the early design partner group. Here is a quick overview of our calm, collaborative take on email...",
                        isDraft: true
                    )
                ],
                isUnread: false,
                isStarred: false,
                tags: ["Draft"]
            ),
            MailThread(
                routeID: "roadmap-notes",
                mailbox: .archive,
                subject: "Roadmap notes from product sync",
                participants: [nora, alex, me],
                messages: [
                    MailMessage(
                        routeID: "roadmap-notes-1",
                        sender: nora,
                        recipients: [alex, me],
                        sentAt: .now.addingTimeInterval(-3600 * 72),
                        body: "Captured the big roadmap themes: faster triage, identity-rich threads, and calmer notifications. I archived the raw notes after cleanup."
                    )
                ],
                isUnread: false,
                isStarred: true,
                tags: ["Product"]
            )
        ]
    }
}