import Foundation

/// A Sendable, Codable JSON value used for feature flags and request variables.
package enum JSONValue: Codable, Hashable, Sendable {
    case null
    case bool(Bool)
    case number(Double)
    case string(String)
    case array([JSONValue])
    case object([String: JSONValue])

    package init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        if container.decodeNil() {
            self = .null
        } else if let value = try? container.decode(Bool.self) {
            self = .bool(value)
        } else if let value = try? container.decode(Double.self) {
            self = .number(value)
        } else if let value = try? container.decode(String.self) {
            self = .string(value)
        } else if let value = try? container.decode([JSONValue].self) {
            self = .array(value)
        } else {
            self = .object(try container.decode([String: JSONValue].self))
        }
    }

    package func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        switch self {
        case .null: try container.encodeNil()
        case .bool(let value): try container.encode(value)
        case .number(let value):
            if value.rounded() == value, abs(value) < 1e15 {
                try container.encode(Int64(value))
            } else {
                try container.encode(value)
            }
        case .string(let value): try container.encode(value)
        case .array(let value): try container.encode(value)
        case .object(let value): try container.encode(value)
        }
    }

    package subscript(key: String) -> JSONValue? {
        if case .object(let object) = self { return object[key] }
        return nil
    }

    package func encodedString() -> String {
        let encoder = JSONEncoder()
        encoder.outputFormatting = [.sortedKeys, .withoutEscapingSlashes]
        return (try? encoder.encode(self)).map { String(decoding: $0, as: UTF8.self) } ?? "{}"
    }
}

extension JSONValue: ExpressibleByStringLiteral, ExpressibleByBooleanLiteral, ExpressibleByIntegerLiteral,
    ExpressibleByDictionaryLiteral, ExpressibleByArrayLiteral, ExpressibleByNilLiteral
{
    package init(stringLiteral value: String) { self = .string(value) }
    package init(booleanLiteral value: Bool) { self = .bool(value) }
    package init(integerLiteral value: Int) { self = .number(Double(value)) }
    package init(dictionaryLiteral elements: (String, JSONValue)...) {
        self = .object(Dictionary(elements, uniquingKeysWith: { $1 }))
    }
    package init(arrayLiteral elements: JSONValue...) { self = .array(elements) }
    package init(nilLiteral: ()) { self = .null }
}