import Foundation

// Shapes of the server JSON (see server/timetable.js and server/directory.js), as in the
// Android client's Models.kt. Missing keys fall back to defaults, so an older or newer
// server never breaks decoding.

struct Timetable: Codable, Hashable {
    var group: String
    var document: DocumentRef
    var period: String?
    var semester: Semester?
    var note: String?
    var subgroups: [String] = []
    var bells: [Bell] = []
    var from: String
    var days: [Day] = []
    var weekly: [WeeklyDay] = []
    var notes: [String] = []
}

struct DocumentRef: Codable, Hashable {
    var id: String
    var name: String
    var faculty: String = ""
    var course: String = ""
    var modified: String?
}

struct Semester: Codable, Hashable {
    var id: String
    var label: String
    var start: String
    var end: String
}

struct Bell: Codable, Hashable {
    var pair: Int
    var start: String
    var end: String
    var halves: [[String]] = []
}

struct Week: Codable, Hashable {
    var n: Int
    var color: String
    var white: Bool { color == "white" }
}

struct Day: Codable, Hashable {
    var date: String
    var weekday: Int
    var week: Week?
    var lessons: [Lesson] = []
}

struct WeeklyDay: Codable, Hashable {
    var day: Int
    var lessons: [Lesson] = []
}

struct Lesson: Codable, Hashable {
    var key: String
    var start: String
    var end: String?
    var pair: Int?
    var subject: String
    var type: String = ""
    var teachers: [String] = []
    var rooms: [String] = []
    var roomMoved: Bool = false
    var distance: Bool = false
    var condition: String = ""
    var variant: String = "all"
    var subgroup: String?
    var groups: [String] = []
    var uncertain: Bool = false
    var raw: String = ""

    /** A recurring lesson the student may hide: the subject with its kind, in every week. */
    var hideKey: String { subject.trimmed.lowercased() + "|" + type.trimmed.lowercased() }
}

struct GroupsResponse: Codable {
    var results: [GroupResult] = []
    var facets: Facets = Facets()
    var total: Int = 0
    var year: String = ""
}

struct GroupResult: Codable, Hashable, Identifiable {
    var group: String
    var fileId: String
    var file: String = ""
    var faculty: String = ""
    var course: String = ""
    var form: String = ""
    var period: String = ""
    var id: String { fileId + "|" + group }
}

struct Facets: Codable {
    var faculties: [Facet] = []
    var courses: [Facet] = []
    var forms: [Facet] = []
}

struct Facet: Codable, Hashable {
    var name: String
    var count: Int
}

struct DirectorySearch: Codable {
    var teachers: [TeacherHit] = []
    var rooms: [RoomHit] = []
}

struct TeacherHit: Codable, Hashable {
    var name: String
    var count: Int = 0
    var faculties: [String] = []
}

struct RoomHit: Codable, Hashable {
    var room: String
    var count: Int = 0
}

struct DirectoryDay: Codable {
    var date: String
    var lessons: [DirectoryLesson] = []
    var coverage: Coverage
}

struct DirectoryLesson: Codable, Hashable {
    var start: String
    var end: String?
    var subject: String
    var type: String = ""
    var teachers: [String] = []
    var rooms: [String] = []
    var moved: Bool = false
    var distance: Bool = false
    var groups: [String] = []
    var condition: String = ""
    var uncertain: Bool = false
}

struct Coverage: Codable {
    var documents: Int
    var total: Int
    var failed: [String] = []
    var withoutSemester: [String] = []
    var year: String = ""
}

struct CalendarInfo: Codable {
    var bells: [Bell] = []
}

/** An exam, credit or consultation of the group, from any document of the catalog (/api/exams). */
struct Exam: Codable, Hashable {
    var date: String
    var start: String
    var end: String?
    var type: String
    var subject: String
    var teachers: [String] = []
    var rooms: [String] = []
    /** Consultations go into the list but not into the countdown. */
    var counts: Bool { type != "Консультация" }
}

struct ExamsResponse: Codable {
    var group: String = ""
    var exams: [Exam] = []
}

/** A group the student opened; kept on the device for quick switching. */
struct SavedGroup: Codable, Hashable {
    var docId: String
    var group: String
    var faculty: String = ""
    var course: String = ""
    /** "docId|group": notes, marks and choices of one group never show up in another. */
    var key: String { docId + "|" + group }
}

/**
 * A homework task or a plain note pinned to one lesson (subject, date, start time),
 * or a general plan with an empty subject. Tasks can be ticked off; notes just remind.
 */
struct Note: Codable, Hashable, Identifiable {
    var id: String = UUID().uuidString
    var group: String
    var subject: String
    var date: String
    var start: String
    var text: String
    var task: Bool = true
    var done: Bool = false
    var created: Double = Date().timeIntervalSince1970 * 1000

    /** A plan not pinned to any lesson: just a day. */
    var general: Bool { subject.trimmed.isEmpty }
}

/** Whether the student was at one lesson. */
struct Mark: Codable, Hashable {
    var group: String
    var subject: String
    var date: String
    var start: String
    var present: Bool
    var id: String { [group, date, start, subject.trimmed.lowercased()].joined(separator: "|") }
}

extension String {
    var trimmed: String { trimmingCharacters(in: .whitespacesAndNewlines) }
}

// MARK: - Lenient decoding

/// Keys may be missing in older answers or caches: every optional field falls back to its default.
extension Timetable {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        group = try c.decode(String.self, forKey: .group)
        document = try c.decode(DocumentRef.self, forKey: .document)
        period = try c.decodeIfPresent(String.self, forKey: .period)
        semester = try c.decodeIfPresent(Semester.self, forKey: .semester)
        note = try c.decodeIfPresent(String.self, forKey: .note)
        subgroups = try c.decodeIfPresent([String].self, forKey: .subgroups) ?? []
        bells = try c.decodeIfPresent([Bell].self, forKey: .bells) ?? []
        from = try c.decodeIfPresent(String.self, forKey: .from) ?? ""
        days = try c.decodeIfPresent([Day].self, forKey: .days) ?? []
        weekly = try c.decodeIfPresent([WeeklyDay].self, forKey: .weekly) ?? []
        notes = try c.decodeIfPresent([String].self, forKey: .notes) ?? []
    }
}

extension DocumentRef {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        id = try c.decode(String.self, forKey: .id)
        name = try c.decodeIfPresent(String.self, forKey: .name) ?? ""
        faculty = try c.decodeIfPresent(String.self, forKey: .faculty) ?? ""
        course = try c.decodeIfPresent(String.self, forKey: .course) ?? ""
        modified = try c.decodeIfPresent(String.self, forKey: .modified)
    }
}

extension Bell {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        pair = try c.decode(Int.self, forKey: .pair)
        start = try c.decode(String.self, forKey: .start)
        end = try c.decode(String.self, forKey: .end)
        halves = try c.decodeIfPresent([[String]].self, forKey: .halves) ?? []
    }
}

extension Day {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        date = try c.decode(String.self, forKey: .date)
        weekday = try c.decodeIfPresent(Int.self, forKey: .weekday) ?? 0
        week = try c.decodeIfPresent(Week.self, forKey: .week)
        lessons = try c.decodeIfPresent([Lesson].self, forKey: .lessons) ?? []
    }
}

extension WeeklyDay {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        day = try c.decode(Int.self, forKey: .day)
        lessons = try c.decodeIfPresent([Lesson].self, forKey: .lessons) ?? []
    }
}

extension Lesson {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        key = try c.decodeIfPresent(String.self, forKey: .key) ?? UUID().uuidString
        start = try c.decode(String.self, forKey: .start)
        end = try c.decodeIfPresent(String.self, forKey: .end)
        pair = try c.decodeIfPresent(Int.self, forKey: .pair)
        subject = try c.decode(String.self, forKey: .subject)
        type = try c.decodeIfPresent(String.self, forKey: .type) ?? ""
        teachers = try c.decodeIfPresent([String].self, forKey: .teachers) ?? []
        rooms = try c.decodeIfPresent([String].self, forKey: .rooms) ?? []
        roomMoved = try c.decodeIfPresent(Bool.self, forKey: .roomMoved) ?? false
        distance = try c.decodeIfPresent(Bool.self, forKey: .distance) ?? false
        condition = try c.decodeIfPresent(String.self, forKey: .condition) ?? ""
        variant = try c.decodeIfPresent(String.self, forKey: .variant) ?? "all"
        subgroup = try c.decodeIfPresent(String.self, forKey: .subgroup)
        groups = try c.decodeIfPresent([String].self, forKey: .groups) ?? []
        uncertain = try c.decodeIfPresent(Bool.self, forKey: .uncertain) ?? false
        raw = try c.decodeIfPresent(String.self, forKey: .raw) ?? ""
    }
}

extension GroupsResponse {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        results = try c.decodeIfPresent([GroupResult].self, forKey: .results) ?? []
        facets = try c.decodeIfPresent(Facets.self, forKey: .facets) ?? Facets()
        total = try c.decodeIfPresent(Int.self, forKey: .total) ?? 0
        year = try c.decodeIfPresent(String.self, forKey: .year) ?? ""
    }
}

extension GroupResult {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        group = try c.decode(String.self, forKey: .group)
        fileId = try c.decode(String.self, forKey: .fileId)
        file = try c.decodeIfPresent(String.self, forKey: .file) ?? ""
        faculty = try c.decodeIfPresent(String.self, forKey: .faculty) ?? ""
        course = try c.decodeIfPresent(String.self, forKey: .course) ?? ""
        form = try c.decodeIfPresent(String.self, forKey: .form) ?? ""
        period = try c.decodeIfPresent(String.self, forKey: .period) ?? ""
    }
}

extension Facets {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        faculties = try c.decodeIfPresent([Facet].self, forKey: .faculties) ?? []
        courses = try c.decodeIfPresent([Facet].self, forKey: .courses) ?? []
        forms = try c.decodeIfPresent([Facet].self, forKey: .forms) ?? []
    }
}

extension DirectorySearch {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        teachers = try c.decodeIfPresent([TeacherHit].self, forKey: .teachers) ?? []
        rooms = try c.decodeIfPresent([RoomHit].self, forKey: .rooms) ?? []
    }
}

extension TeacherHit {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        name = try c.decode(String.self, forKey: .name)
        count = try c.decodeIfPresent(Int.self, forKey: .count) ?? 0
        faculties = try c.decodeIfPresent([String].self, forKey: .faculties) ?? []
    }
}

extension RoomHit {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        room = try c.decode(String.self, forKey: .room)
        count = try c.decodeIfPresent(Int.self, forKey: .count) ?? 0
    }
}

extension DirectoryDay {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        date = try c.decode(String.self, forKey: .date)
        lessons = try c.decodeIfPresent([DirectoryLesson].self, forKey: .lessons) ?? []
        coverage = try c.decode(Coverage.self, forKey: .coverage)
    }
}

extension DirectoryLesson {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        start = try c.decode(String.self, forKey: .start)
        end = try c.decodeIfPresent(String.self, forKey: .end)
        subject = try c.decode(String.self, forKey: .subject)
        type = try c.decodeIfPresent(String.self, forKey: .type) ?? ""
        teachers = try c.decodeIfPresent([String].self, forKey: .teachers) ?? []
        rooms = try c.decodeIfPresent([String].self, forKey: .rooms) ?? []
        moved = try c.decodeIfPresent(Bool.self, forKey: .moved) ?? false
        distance = try c.decodeIfPresent(Bool.self, forKey: .distance) ?? false
        groups = try c.decodeIfPresent([String].self, forKey: .groups) ?? []
        condition = try c.decodeIfPresent(String.self, forKey: .condition) ?? ""
        uncertain = try c.decodeIfPresent(Bool.self, forKey: .uncertain) ?? false
    }
}

extension Coverage {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        documents = try c.decodeIfPresent(Int.self, forKey: .documents) ?? 0
        total = try c.decodeIfPresent(Int.self, forKey: .total) ?? 0
        failed = try c.decodeIfPresent([String].self, forKey: .failed) ?? []
        withoutSemester = try c.decodeIfPresent([String].self, forKey: .withoutSemester) ?? []
        year = try c.decodeIfPresent(String.self, forKey: .year) ?? ""
    }
}

extension CalendarInfo {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        bells = try c.decodeIfPresent([Bell].self, forKey: .bells) ?? []
    }
}

extension Exam {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        date = try c.decode(String.self, forKey: .date)
        start = try c.decodeIfPresent(String.self, forKey: .start) ?? ""
        end = try c.decodeIfPresent(String.self, forKey: .end)
        type = try c.decodeIfPresent(String.self, forKey: .type) ?? ""
        subject = try c.decode(String.self, forKey: .subject)
        teachers = try c.decodeIfPresent([String].self, forKey: .teachers) ?? []
        rooms = try c.decodeIfPresent([String].self, forKey: .rooms) ?? []
    }
}

extension ExamsResponse {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        group = try c.decodeIfPresent(String.self, forKey: .group) ?? ""
        exams = try c.decodeIfPresent([Exam].self, forKey: .exams) ?? []
    }
}

extension SavedGroup {
    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        docId = try c.decode(String.self, forKey: .docId)
        group = try c.decode(String.self, forKey: .group)
        faculty = try c.decodeIfPresent(String.self, forKey: .faculty) ?? ""
        course = try c.decodeIfPresent(String.self, forKey: .course) ?? ""
    }
}