import Foundation

/// Pure helpers for session-folder names. A session folder is created at start
/// with an auto name `<yyyy-MM-dd'T'HH-mm-ss>_<app>`; when the user names the
/// recording on stop it's renamed to `<yyyy-MM-dd>_<name>_<app>` (no HH-MM-SS),
/// which is far easier to scan in `sessions/`. The app label always stays the
/// LAST `_`-separated segment so `SessionController.appLabel(from:)` keeps working
/// even when the meeting name itself contains spaces or underscores.
enum SessionNaming {
    /// Filesystem- and parse-safe meeting name: trims, turns path separators into
    /// dashes, drops control characters, collapses whitespace runs, removes leading
    /// dots (no hidden/`.`/`..` folders), and caps the length. Returns "" if nothing
    /// usable is left, which callers treat as "skip the rename".
    static func sanitize(_ raw: String) -> String {
        var s = raw.trimmingCharacters(in: .whitespacesAndNewlines)
        // Path-hostile separators (`/` and the classic Mac `:`, plus `\`) → dash.
        s = s.components(separatedBy: CharacterSet(charactersIn: "/:\\")).joined(separator: "-")
        // Strip control characters outright.
        s = s.components(separatedBy: .controlCharacters).joined()
        // Collapse internal whitespace runs to single spaces.
        s = s.split(whereSeparator: { $0 == " " || $0 == "\t" }).joined(separator: " ")
        while s.hasPrefix(".") { s.removeFirst() }
        s = s.trimmingCharacters(in: .whitespaces)
        if s.count > 60 { s = String(s.prefix(60)).trimmingCharacters(in: .whitespaces) }
        return s
    }

    /// The date prefix of a session leaf name, e.g. `2026-06-17T09-59-48_signal`
    /// → `2026-06-17`. Already-renamed leaves (`2026-06-17_name_signal`) return the
    /// same date, so this is safe to call on either form.
    static func datePrefix(ofSessionNamed leaf: String) -> String {
        let head = leaf.split(separator: "_").first.map(String.init) ?? leaf
        return head.split(separator: "T").first.map(String.init) ?? head
    }

    /// Compose the renamed leaf `<date>_<name>_<app>`. A positive `counter`
    /// disambiguates a collision by suffixing the NAME segment (`<name>-2`) so the
    /// trailing `_<app>` stays parseable. Returns nil when the name sanitizes to
    /// empty (the caller keeps the auto timestamped name).
    static func renamedLeaf(date: String, app: String, meetingName: String, counter: Int = 0) -> String? {
        let clean = sanitize(meetingName)
        guard !clean.isEmpty else { return nil }
        let suffix = counter > 0 ? "-\(counter + 1)" : ""
        return "\(date)_\(clean)\(suffix)_\(app)"
    }

    /// Friendly recap title from a session id, understanding both folder forms:
    ///   `2026-06-06T11-43-02_meet` → "Google Meet call — 2026-06-06 11:43"
    ///   `2026-06-06_Weekly sync_meet` → "Weekly sync — Google Meet (2026-06-06)"
    static func recapTitle(app: String, sessionId: String) -> String {
        let appName = CallDetector.DetectedApp(rawValue: app)?.display ?? app.capitalized
        var parts = sessionId.split(separator: "_").map(String.init)
        if parts.count > 1 { parts.removeLast() }   // drop the trailing "_<app>"
        let head = parts.first ?? sessionId
        let tBits = head.split(separator: "T").map(String.init)
        let date = tBits.first ?? head
        let time: String = {
            guard tBits.count > 1 else { return "" }
            let b = tBits[1].split(separator: "-")
            return b.count >= 2 ? "\(b[0]):\(b[1])" : ""
        }()
        let when = [date, time].filter { !$0.isEmpty }.joined(separator: " ")
        // Rejoin with "_" — the faithful inverse of split("_") — so a name that
        // itself contained underscores survives the round-trip through the folder name.
        let name = parts.count > 1 ? parts[1...].joined(separator: "_") : ""
        if name.isEmpty {
            return "\(appName) call — \(when)".trimmingCharacters(in: .whitespaces)
        }
        return "\(name) — \(appName) (\(when))".trimmingCharacters(in: .whitespaces)
    }
}