// Sources/SwiftProtobuf/NameMap.swift - Bidirectional number/name mapping

//

// Copyright (c) 2014 - 2016 Apple Inc. and the project authors

// Licensed under Apache License v2.0 with Runtime Library Exception

//

// See LICENSE.txt for license information:

// https://github.com/apple/swift-protobuf/blob/main/LICENSE.txt

//

// -----------------------------------------------------------------------------

/// TODO: Right now, only the NameMap and the NameDescription enum

/// (which are directly used by the generated code) are public.

/// This means that code outside the library has no way to actually

/// use this data.  We should develop and publicize a suitable API

/// for that purpose.  (Which might be the same as the internal API.)

/// This must produce exactly the same outputs as the corresponding

/// code in the protoc-gen-swift code generator. Changing it will

/// break compatibility of the library with older generated code.

///

/// It does not necessarily need to match protoc's JSON field naming

/// logic, however.

private func toJSONFieldName(_ s: UnsafeBufferPointer<UInt8>) -> String {

    var result = String.UnicodeScalarView()

    var capitalizeNext = false

    for c in s {

        if c == UInt8(ascii: "_") {

            capitalizeNext = true

        } else if capitalizeNext {

            result.append(Unicode.Scalar(c).uppercasedAssumingASCII)

            capitalizeNext = false

        } else {

            result.append(Unicode.Scalar(c))

        }

    }

    return String(result)

}

#if !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

private func toJSONFieldName(_ s: StaticString) -> String {

    guard s.hasPointerRepresentation else {

        // If it's a single code point, it wouldn't be changed by the above algorithm.

        // Return it as-is.

        return s.description

    }

    return toJSONFieldName(UnsafeBufferPointer(start: s.utf8Start, count: s.utf8CodeUnitCount))

}

#endif  // !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

/// Allocate static memory buffers to intern UTF-8

/// string data.  Track the buffers and release all of those buffers

/// in case we ever get deallocated.

private class InternPool {

    private var interned = [UnsafeRawBufferPointer]()

    func intern(utf8: String.UTF8View) -> UnsafeRawBufferPointer {

        let mutable = UnsafeMutableRawBufferPointer.allocate(

            byteCount: utf8.count,

            alignment: MemoryLayout<UInt8>.alignment

        )

        mutable.copyBytes(from: utf8)

        let immutable = UnsafeRawBufferPointer(mutable)

        interned.append(immutable)

        return immutable

    }

    func intern(utf8Ptr: UnsafeBufferPointer<UInt8>) -> UnsafeRawBufferPointer {

        let mutable = UnsafeMutableRawBufferPointer.allocate(

            byteCount: utf8Ptr.count,

            alignment: MemoryLayout<UInt8>.alignment

        )

        mutable.copyBytes(from: utf8Ptr)

        let immutable = UnsafeRawBufferPointer(mutable)

        interned.append(immutable)

        return immutable

    }

    deinit {

        for buff in interned {

            buff.deallocate()

        }

    }

}

/// Instructions used in bytecode streams that define proto name mappings.

///

/// Since field and enum case names are encoded in numeric order, field and case number operands in

/// the bytecode are stored as adjacent differences. Most messages/enums use densely packed

/// numbers, so we've optimized the opcodes for that; each instruction that takes a single

/// field/case number has two forms: one that assumes the next number is +1 from the previous

/// number, and a second form that takes an arbitrary delta from the previous number.

///

/// This has package visibility so that it is also visible to the generator.

package enum ProtoNameInstruction: UInt64, CaseIterable {

    /// The proto (text format) name and the JSON name are the same string.

    ///

    /// ## Operands

    /// * (Delta only) An integer representing the (delta from the previous) field or enum case

    ///   number.

    /// * A string containing the single text format and JSON name.

    case sameNext = 1

    case sameDelta = 2

    /// The JSON name can be computed from the proto string.

    ///

    /// ## Operands

    /// * (Delta only) An integer representing the (delta from the previous) field or enum case

    ///   number.

    /// * A string containing the single text format name, from which the JSON name will be

    ///   dynamically computed.

    case standardNext = 3

    case standardDelta = 4

    /// The JSON and text format names are just different.

    ///

    /// ## Operands

    /// * (Delta only) An integer representing the (delta from the previous) field or enum case

    ///   number.

    /// * A string containing the text format name.

    /// * A string containing the JSON name.

    case uniqueNext = 5

    case uniqueDelta = 6

    /// Used for group fields only to represent the message type name of a group.

    ///

    /// ## Operands

    /// * (Delta only) An integer representing the (delta from the previous) field number.

    /// * A string containing the (UpperCamelCase by convention) message type name, from which the

    ///   text format and JSON names can be derived (lowercase).

    case groupNext = 7

    case groupDelta = 8

    /// Used for enum cases only to represent a value's primary proto name (the first defined case)

    /// and its aliases. The JSON and text format names for enums are always the same.

    ///

    /// ## Operands

    /// * (Delta only) An integer representing the (delta from the previous) enum case number.

    /// * An integer `aliasCount` representing the number of aliases.

    /// * A string containing the text format/JSON name (the first defined case with this number).

    /// * `aliasCount` strings containing other text format/JSON names that are aliases.

    case aliasNext = 9

    case aliasDelta = 10

    /// Represents a reserved name in a proto message.

    ///

    /// ## Operands

    /// * The name of a reserved field.

    case reservedName = 11

    /// Represents a range of reserved field numbers or enum case numbers in a proto message.

    ///

    /// ## Operands

    /// * An integer representing the lower bound (inclusive) of the reserved number range.

    /// * An integer representing the delta between the upper bound (exclusive) and the lower bound

    ///   of the reserved number range.

    case reservedNumbers = 12

    /// Indicates whether the opcode represents an instruction that has an explicit delta encoded

    /// as its first operand.

    var hasExplicitDelta: Bool {

        switch self {

        case .sameDelta, .standardDelta, .uniqueDelta, .groupDelta, .aliasDelta: return true

        default: return false

        }

    }

}

/// An immutable bidirectional mapping between field/enum-case names

/// and numbers, used to record field names for text-based

/// serialization (JSON and text).  These maps are lazily instantiated

/// for each message as needed, so there is no run-time overhead for

/// users who do not use text-based serialization formats.

public struct _NameMap: ExpressibleByDictionaryLiteral {

    /// An immutable interned string container.  The `utf8Start` pointer

    /// is guaranteed valid for the lifetime of the `NameMap` that you

    /// fetched it from.  Since `NameMap`s are only instantiated as

    /// immutable static values, that should be the lifetime of the

    /// program.

    ///

    /// Internally, this uses `StaticString` (which refers to a fixed

    /// block of UTF-8 data) where possible.  In cases where the string

    /// has to be computed, it caches the UTF-8 bytes in an

    /// unmovable and immutable heap area.

    package struct Name: Hashable, CustomStringConvertible {

        #if !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

        // This should not be used outside of this file, as it requires

        // coordinating the lifecycle with the lifecycle of the pool

        // where the raw UTF8 gets interned.

        fileprivate init(staticString: StaticString, pool: InternPool) {

            if staticString.hasPointerRepresentation {

                self.utf8Buffer = UnsafeRawBufferPointer(

                    start: staticString.utf8Start,

                    count: staticString.utf8CodeUnitCount

                )

            } else {

                self.utf8Buffer = staticString.withUTF8Buffer { pool.intern(utf8Ptr: $0) }

            }

        }

        #endif  // !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

        // This should not be used outside of this file, as it requires

        // coordinating the lifecycle with the lifecycle of the pool

        // where the raw UTF8 gets interned.

        fileprivate init(string: String, pool: InternPool) {

            let utf8 = string.utf8

            self.utf8Buffer = pool.intern(utf8: utf8)

        }

        // This is for building a transient `Name` object sufficient for lookup purposes.

        // It MUST NOT be exposed outside of this file.

        fileprivate init(transientUtf8Buffer: UnsafeRawBufferPointer) {

            self.utf8Buffer = transientUtf8Buffer

        }

        // This is for building a `Name` object from a slice of a bytecode `StaticString`.

        // It MUST NOT be exposed outside of this file.

        fileprivate init(bytecodeUTF8Buffer: UnsafeBufferPointer<UInt8>) {

            self.utf8Buffer = UnsafeRawBufferPointer(bytecodeUTF8Buffer)

        }

        internal let utf8Buffer: UnsafeRawBufferPointer

        public var description: String {

            String(decoding: self.utf8Buffer, as: UTF8.self)

        }

        public func hash(into hasher: inout Hasher) {

            for byte in utf8Buffer {

                hasher.combine(byte)

            }

        }

        public static func == (lhs: Name, rhs: Name) -> Bool {

            if lhs.utf8Buffer.count != rhs.utf8Buffer.count {

                return false

            }

            return lhs.utf8Buffer.elementsEqual(rhs.utf8Buffer)

        }

    }

    /// The JSON and proto names for a particular field, enum case, or extension.

    internal struct Names {

        private(set) var json: Name?

        private(set) var proto: Name

    }

    #if !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

    /// A description of the names for a particular field or enum case.

    /// The different forms here let us minimize the amount of string

    /// data that we store in the binary.

    ///

    /// These are only used in the generated code to initialize a NameMap.

    public enum NameDescription {

        /// The proto (text format) name and the JSON name are the same string.

        case same(proto: StaticString)

        /// The JSON name can be computed from the proto string

        case standard(proto: StaticString)

        /// The JSON and text format names are just different.

        case unique(proto: StaticString, json: StaticString)

        /// Used for enum cases only to represent a value's primary proto name (the

        /// first defined case) and its aliases. The JSON and text format names for

        /// enums are always the same.

        case aliased(proto: StaticString, aliases: [StaticString])

    }

    #endif  // !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

    private var internPool = InternPool()

    /// The mapping from field/enum-case numbers to names.

    private var numberToNameMap: [Int: Names] = [:]

    /// The mapping from proto/text names to field/enum-case numbers.

    private var protoToNumberMap: [Name: Int] = [:]

    /// The mapping from JSON names to field/enum-case numbers.

    /// Note that this also contains all of the proto/text names,

    /// as required by Google's spec for protobuf JSON.

    private var jsonToNumberMap: [Name: Int] = [:]

    /// The reserved names in for this object. Currently only used for Message to

    /// support TextFormat's requirement to skip these names in all cases.

    private var reservedNames: [String] = []

    /// The reserved numbers in for this object. Currently only used for Message to

    /// support TextFormat's requirement to skip these numbers in all cases.

    private var reservedRanges: [Range<Int32>] = []

    /// Creates a new empty field/enum-case name/number mapping.

    public init() {}

    #if REMOVE_LEGACY_NAMEMAP_INITIALIZERS

    // Provide a dummy for ExpressibleByDictionaryLiteral conformance.

    public init(dictionaryLiteral elements: (Int, Int)...) {

        fatalError("Support compiled out removed")

    }

    #else  // !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

    /// Build the bidirectional maps between numbers and proto/JSON names.

    public init(

        reservedNames: [String],

        reservedRanges: [Range<Int32>],

        numberNameMappings: KeyValuePairs<Int, NameDescription>

    ) {

        self.reservedNames = reservedNames

        self.reservedRanges = reservedRanges

        initHelper(numberNameMappings)

    }

    /// Build the bidirectional maps between numbers and proto/JSON names.

    public init(dictionaryLiteral elements: (Int, NameDescription)...) {

        initHelper(elements)

    }

    /// Helper to share the building of mappings between the two initializers.

    private mutating func initHelper<Pairs: Collection>(

        _ elements: Pairs

    ) where Pairs.Element == (key: Int, value: NameDescription) {

        for (number, description) in elements {

            switch description {

            case .same(proto: let p):

                let protoName = Name(staticString: p, pool: internPool)

                let names = Names(json: protoName, proto: protoName)

                numberToNameMap[number] = names

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

            case .standard(proto: let p):

                let protoName = Name(staticString: p, pool: internPool)

                let jsonString = toJSONFieldName(p)

                let jsonName = Name(string: jsonString, pool: internPool)

                let names = Names(json: jsonName, proto: protoName)

                numberToNameMap[number] = names

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

                jsonToNumberMap[jsonName] = number

            case .unique(proto: let p, json: let j):

                let jsonName = Name(staticString: j, pool: internPool)

                let protoName = Name(staticString: p, pool: internPool)

                let names = Names(json: jsonName, proto: protoName)

                numberToNameMap[number] = names

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

                jsonToNumberMap[jsonName] = number

            case .aliased(proto: let p, let aliases):

                let protoName = Name(staticString: p, pool: internPool)

                let names = Names(json: protoName, proto: protoName)

                numberToNameMap[number] = names

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

                for alias in aliases {

                    let protoName = Name(staticString: alias, pool: internPool)

                    protoToNumberMap[protoName] = number

                    jsonToNumberMap[protoName] = number

                }

            }

        }

    }

    #endif  // !REMOVE_LEGACY_NAMEMAP_INITIALIZERS

    public init(bytecode: StaticString) {

        var previousNumber = 0

        BytecodeInterpreter<ProtoNameInstruction>(program: bytecode).execute { instruction, reader in

            func nextNumber() -> Int {

                let next: Int

                if instruction.hasExplicitDelta {

                    next = previousNumber + Int(reader.nextInt32())

                } else {

                    next = previousNumber + 1

                }

                previousNumber = next

                return next

            }

            switch instruction {

            case .sameNext, .sameDelta:

                let number = nextNumber()

                let protoName = Name(bytecodeUTF8Buffer: reader.nextNullTerminatedString())

                numberToNameMap[number] = Names(json: protoName, proto: protoName)

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

            case .standardNext, .standardDelta:

                let number = nextNumber()

                let protoNameBuffer = reader.nextNullTerminatedString()

                let protoName = Name(bytecodeUTF8Buffer: protoNameBuffer)

                let jsonString = toJSONFieldName(protoNameBuffer)

                let jsonName = Name(string: jsonString, pool: internPool)

                numberToNameMap[number] = Names(json: jsonName, proto: protoName)

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

                jsonToNumberMap[jsonName] = number

            case .uniqueNext, .uniqueDelta:

                let number = nextNumber()

                let protoName = Name(bytecodeUTF8Buffer: reader.nextNullTerminatedString())

                let jsonName = Name(bytecodeUTF8Buffer: reader.nextNullTerminatedString())

                numberToNameMap[number] = Names(json: jsonName, proto: protoName)

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

                jsonToNumberMap[jsonName] = number

            case .groupNext, .groupDelta:

                let number = nextNumber()

                let protoNameBuffer = reader.nextNullTerminatedString()

                let protoName = Name(bytecodeUTF8Buffer: protoNameBuffer)

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

                let lowercaseName: Name

                let hasUppercase = protoNameBuffer.contains { (UInt8(ascii: "A")...UInt8(ascii: "Z")).contains($0) }

                if hasUppercase {

                    lowercaseName = Name(

                        string: String(decoding: protoNameBuffer, as: UTF8.self).lowercased(),

                        pool: internPool

                    )

                    protoToNumberMap[lowercaseName] = number

                    jsonToNumberMap[lowercaseName] = number

                } else {

                    // No need to convert and intern a separate copy of the string

                    // if it would be identical.

                    lowercaseName = protoName

                }

                numberToNameMap[number] = Names(json: lowercaseName, proto: protoName)

            case .aliasNext, .aliasDelta:

                let number = nextNumber()

                let protoName = Name(bytecodeUTF8Buffer: reader.nextNullTerminatedString())

                numberToNameMap[number] = Names(json: protoName, proto: protoName)

                protoToNumberMap[protoName] = number

                jsonToNumberMap[protoName] = number

                for alias in reader.nextNullTerminatedStringArray() {

                    let protoName = Name(bytecodeUTF8Buffer: alias)

                    protoToNumberMap[protoName] = number

                    jsonToNumberMap[protoName] = number

                }

            case .reservedName:

                let name = String(decoding: reader.nextNullTerminatedString(), as: UTF8.self)

                reservedNames.append(name)

            case .reservedNumbers:

                let lowerBound = reader.nextInt32()

                let upperBound = lowerBound + reader.nextInt32()

                reservedRanges.append(lowerBound..<upperBound)

            }

        }

    }

    /// Returns the name bundle for the field/enum-case with the given number, or

    /// `nil` if there is no match.

    internal func names(for number: Int) -> Names? {

        numberToNameMap[number]

    }

    /// Returns the field/enum-case number that has the given JSON name,

    /// or `nil` if there is no match.

    ///

    /// This is used by the Text format parser to look up field or enum

    /// names using a direct reference to the un-decoded UTF8 bytes.

    internal func number(forProtoName raw: UnsafeRawBufferPointer) -> Int? {

        let n = Name(transientUtf8Buffer: raw)

        return protoToNumberMap[n]

    }

    /// Returns the field/enum-case number that has the given JSON name,

    /// or `nil` if there is no match.

    ///

    /// This accepts a regular `String` and is used in JSON parsing

    /// only when a field name or enum name was decoded from a string

    /// containing backslash escapes.

    ///

    /// JSON parsing must interpret *both* the JSON name of the

    /// field/enum-case provided by the descriptor *as well as* its

    /// original proto/text name.

    internal func number(forJSONName name: String) -> Int? {

        let utf8 = Array(name.utf8)

        return utf8.withUnsafeBytes { (buffer: UnsafeRawBufferPointer) in

            let n = Name(transientUtf8Buffer: buffer)

            return jsonToNumberMap[n]

        }

    }

    /// Returns the field/enum-case number that has the given JSON name,

    /// or `nil` if there is no match.

    ///

    /// This is used by the JSON parser when a field name or enum name

    /// required no special processing.  As a result, we can avoid

    /// copying the name and look up the number using a direct reference

    /// to the un-decoded UTF8 bytes.

    internal func number(forJSONName raw: UnsafeRawBufferPointer) -> Int? {

        let n = Name(transientUtf8Buffer: raw)

        return jsonToNumberMap[n]

    }

    /// Returns all proto names

    internal var names: [Name] {

        numberToNameMap.map(\.value.proto)

    }

    /// Returns if the given name was reserved.

    internal func isReserved(name: UnsafeRawBufferPointer) -> Bool {

        guard !reservedNames.isEmpty,

            let baseAddress = name.baseAddress,

            let s = utf8ToString(bytes: baseAddress, count: name.count)

        else {

            return false

        }

        return reservedNames.contains(s)

    }

    /// Returns if the given number was reserved.

    internal func isReserved(number: Int32) -> Bool {

        for range in reservedRanges {

            if range.contains(number) {

                return true

            }

        }

        return false

    }

}

// The `_NameMap` (and supporting types) are only mutated during their initial

// creation, then for the lifetime of the a process they are constant. Swift

// 5.10 flags the generated `_protobuf_nameMap` usages as a problem

// (https://github.com/apple/swift-protobuf/issues/1560) so this silences those

// warnings since the usage has been deemed safe.

//

// https://github.com/apple/swift-protobuf/issues/1561 is also opened to revisit

// the `_NameMap` generally as it dates back to the days before Swift perferred

// the UTF-8 internal encoding.

extension _NameMap: Sendable {}

extension _NameMap.Name: @unchecked Sendable {}

extension InternPool: @unchecked Sendable {}