//
//  PreferenceValue.swift
//
//  Copyright 2026 Brendan Szymanski <hello@bscubed.dev>
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
//
//  SPDX-License-Identifier: GPL-3.0-or-later
//

import Foundation

/// Converts a Swift preference type to and from a SQLite scalar value.
package protocol PreferenceValue: Sendable, Equatable {
    /// Decodes a value read back from storage, or `nil` when the stored shape does not match.
    ///
    /// - Parameter preference: The raw value read from the preference table.
    /// - Returns: A decoded value, or `nil` when the storage representation is incompatible.
    init?(preference: StoredPreference)

    /// The storage representation of this value.
    var preferenceValue: StoredPreference { get }
}

extension Bool: PreferenceValue {
    package init?(preference: StoredPreference) {
        guard case .integer(let value) = preference, value == 0 || value == 1 else { return nil }
        self = value == 1
    }

    package var preferenceValue: StoredPreference { .integer(self ? 1 : 0) }
}

extension Int: PreferenceValue {
    package init?(preference: StoredPreference) {
        guard case .integer(let value) = preference, let value = Int(exactly: value) else { return nil }
        self = value
    }

    package var preferenceValue: StoredPreference { .integer(Int64(self)) }
}

extension Double: PreferenceValue {
    package init?(preference: StoredPreference) {
        switch preference {
        case .real(let value): self = value
        case .integer(let value): self = Double(value)
        default: return nil
        }
    }

    /// Non-finite values are encoded as zero because SQLite stores NaN as SQL NULL.
    package var preferenceValue: StoredPreference { .real(isFinite ? self : 0) }
}

extension String: PreferenceValue {
    package init?(preference: StoredPreference) {
        guard case .text(let value) = preference else { return nil }
        self = value
    }

    package var preferenceValue: StoredPreference { .text(self) }
}

extension URL: PreferenceValue {
    package init?(preference: StoredPreference) {
        guard case .text(let value) = preference, let url = URL(string: value) else { return nil }
        self = url
    }

    package var preferenceValue: StoredPreference { .text(absoluteString) }
}

extension UUID: PreferenceValue {
    package init?(preference: StoredPreference) {
        guard case .text(let value) = preference, let uuid = UUID(uuidString: value) else { return nil }
        self = uuid
    }

    package var preferenceValue: StoredPreference { .text(uuidString) }
}

extension Data: PreferenceValue {
    package init?(preference: StoredPreference) {
        guard case .blob(let value) = preference else { return nil }
        self = value
    }

    package var preferenceValue: StoredPreference { .blob(self) }
}

extension PreferenceValue where Self: RawRepresentable, Self.RawValue: PreferenceValue {
    package init?(preference: StoredPreference) {
        guard let raw = RawValue(preference: preference) else { return nil }
        self.init(rawValue: raw)
    }

    package var preferenceValue: StoredPreference { rawValue.preferenceValue }
}