//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2021-2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//

/// AST entities that can be pretty-printed or dumped.
///
/// As an alternative to this protocol,
/// you can also use the `description` to pretty-print an AST,
/// and `debugDescription` for to dump a debugging representation.
public protocol _ASTPrintable:
  CustomStringConvertible,
  CustomDebugStringConvertible
{
  // The "base" dump out for AST nodes, like `alternation`.
  // Children printing, parens, etc., handled automatically
  var _dumpBase: String { get }

}
extension _ASTPrintable {
  public var description: String { _print() }
  public var debugDescription: String { _dump() }

  var _children: [AST.Node]? {
    if let children = (self as? _ASTParent)?.children {
      return children
    }
    if let children = (self as? AST.Node)?.children {
      return children
    }
    return nil
  }

  func _print() -> String {
    // TODO: prettier printing
    _dump()
  }
  func _dump() -> String {
    guard let children = _children else {
      return _dumpBase
    }
    let childDump = children.compactMap { child -> String? in
      // Exclude trivia for now, as we don't want it to appear when performing
      // comparisons of dumped output in tests.
      // TODO: We should eventually have some way of filtering out trivia for
      // tests, so that it can appear in regular dumps.
      if child.isTrivia { return nil }
      let dump = child._dump()
      return !dump.isEmpty ? dump : nil
    }
    let base = "\(_dumpBase)"
    if childDump.isEmpty {
      return base
    }
    if childDump.count == 1, base.isEmpty {
      return "\(childDump[0])"
    }
    return "\(base)(\(childDump.joined(separator: ",")))"
  }
}

extension AST: _ASTPrintable {
  public var _dumpBase: String {
    var result = ""
    if let opts = globalOptions {
      result += "\(opts) "
    }
    result += root._dump()
    return result
  }
}

extension AST.Node: _ASTPrintable {
  public var _dumpBase: String {
    _associatedValue._dumpBase
  }
}

extension AST.Alternation {
  public var _dumpBase: String { "alternation<\(children.count)>" }
}

extension AST.Concatenation {
  public var _dumpBase: String { "" }
}

extension AST.Quote {
  public var _dumpBase: String { "quote \"\(literal)\"" }
}

extension AST.Trivia {
  public var _dumpBase: String {
    // TODO: comments, non-semantic whitespace, etc.
    ""
  }
}

extension AST.Interpolation {
  public var _dumpBase: String { "interpolation <\(contents)>" }
}

extension AST.Empty {
  public var _dumpBase: String { "" }
}

extension AST.Conditional {
  public var _dumpBase: String {
    "if \(condition) then \(trueBranch) else \(falseBranch)"
  }
}

extension AST.Conditional.Condition: _ASTPrintable {
  public var _dumpBase: String { return "\(kind)" }
}
extension AST.Conditional.Condition.PCREVersionCheck.Kind: _ASTPrintable {
  public var _dumpBase: String {
    switch self {
    case .equal:              return "="
    case .greaterThanOrEqual: return ">="
    }
  }
}
extension AST.Conditional.Condition.PCREVersionNumber: _ASTPrintable {
  public var _dumpBase: String { "\(major).\(minor)" }
}
extension AST.Conditional.Condition.PCREVersionCheck: _ASTPrintable {
  public var _dumpBase: String { "VERSION\(kind.value)\(num)" }
}

extension AST.Atom {
  public var _dumpBase: String {
    if let lit = self.literalStringValue {
      return lit.halfWidthCornerQuoted
    }

    switch kind {
    case .escaped(let c): return "\\\(c.character)"

    case .scalarSequence(let s):
      return s.scalars.map(\.value.halfWidthCornerQuoted).joined()

    case .namedCharacter(let charName):
      return "\\N{\(charName)}"

    case .property(let p): return "\(p._dumpBase)"

    case .keyboardControl, .keyboardMeta, .keyboardMetaControl:
      fatalError("TODO")

    case .dot:          return "."
    case .caretAnchor:  return "^"
    case .dollarAnchor: return "$"

    case .backreference(let r), .subpattern(let r):
      return "\(r._dumpBase)"

    case .callout(let c): return "\(c)"

    case .backtrackingDirective(let d): return "\(d)"

    case .changeMatchingOptions(let opts):
      return "changeMatchingOptions<\(opts)>"

    case .invalid:
      return "<invalid>"

    case .char, .scalar:
      fatalError("Unreachable")
    }
  }
}

extension AST.Atom.Number: _ASTPrintable {
  public var _dumpBase: String {
    value.map { "\($0)" } ?? "<invalid>"
  }
}

extension AST.Atom.Callout: _ASTPrintable {
  public var _dumpBase: String {
    switch self {
    case .pcre(let p):                  return "\(p)"
    case .onigurumaNamed(let o):        return "\(o)"
    case .onigurumaOfContents(let o):   return "\(o)"
    }
  }
}

extension AST.Atom.Callout.PCRE: _ASTPrintable {
  public var _dumpBase: String {
    "PCRE callout \(arg.value)"
  }
}

extension AST.Atom.Callout.OnigurumaTag: _ASTPrintable {
  public var _dumpBase: String { "[\(name.value)]" }
}

extension AST.Atom.Callout.OnigurumaNamed.ArgList: _ASTPrintable {
  public var _dumpBase: String {
    "{\(args.map { $0.value }.joined(separator: ","))}"
  }
}

extension AST.Atom.Callout.OnigurumaNamed: _ASTPrintable {
  public var _dumpBase: String {
    var result = "named oniguruma callout \(name.value)"
    if let tag = tag {
      result += "\(tag)"
    }
    if let args = args {
      result += "\(args)"
    }
    return result
  }
}

extension AST.Atom.Callout.OnigurumaOfContents: _ASTPrintable {
  public var _dumpBase: String {
    var result = "oniguruma callout of contents {\(contents.value)}"
    if let tag = tag {
      result += "\(tag)"
    }
    result += " \(direction.value)"
    return result
  }
}

extension AST.Reference: _ASTPrintable {
  public var _dumpBase: String {
    var result = "\(kind)"
    if let recursionLevel = recursionLevel {
      result += "\(recursionLevel)"
    }
    return result
  }
}

extension AST.Group.Kind: _ASTPrintable {
  public var _dumpBase: String {
    switch self {
    case .capture:                        return "capture"
    case .namedCapture(let s):            return "capture<\(s.value)>"
    case .balancedCapture(let b):         return "balanced capture \(b)"
    case .nonCapture:                     return "nonCapture"
    case .nonCaptureReset:                return "nonCaptureReset"
    case .atomicNonCapturing:             return "atomicNonCapturing"
    case .lookahead:                      return "lookahead"
    case .negativeLookahead:              return "negativeLookahead"
    case .nonAtomicLookahead:             return "nonAtomicLookahead"
    case .lookbehind:                     return "lookbehind"
    case .negativeLookbehind:             return "negativeLookbehind"
    case .nonAtomicLookbehind:            return "nonAtomicLookbehind"
    case .scriptRun:                      return "scriptRun"
    case .atomicScriptRun:                return "atomicScriptRun"
    case .changeMatchingOptions(let seq): return "changeMatchingOptions<\(seq)>"
    }
  }
}

extension AST.Group: _ASTPrintable {
  public var _dumpBase: String {
    "group_\(kind.value._dumpBase)"
  }
}

extension AST.Quantification.Amount: _ASTPrintable {
  public var _printBase: String {
    _canonicalBase
  }
  public var _dumpBase: String {
    switch self {
    case .zeroOrMore:      return "zeroOrMore"
    case .oneOrMore:       return "oneOrMore"
    case .zeroOrOne:       return "zeroOrOne"
    case let .exactly(n):  return "exactly<\(n)>"
    case let .nOrMore(n):  return "nOrMore<\(n)>"
    case let .upToN(n):    return "uptoN<\(n)>"
    case let .range(lower, upper):
      return ".range<\(lower)...\(upper)>"
    }
  }
}
extension AST.Quantification.Kind: _ASTPrintable {
  public var _printBase: String { rawValue }
  public var _dumpBase: String {
    switch self {
    case .eager:      return "eager"
    case .reluctant:  return "reluctant"
    case .possessive: return "possessive"
    }
  }
}

extension AST.Quantification: _ASTPrintable {
  public var _printBase: String {
    """
    quant_\(amount.value._printBase)\(kind.value._printBase)
    """
  }

  public var _dumpBase: String {
    """
    quant_\(amount.value._dumpBase)_\(kind.value._dumpBase)
    """
  }
}

extension AST.CustomCharacterClass: _ASTNode {
  public var _dumpBase: String {
    // Exclude trivia for now, as we don't want it to appear when performing
    // comparisons of dumped output in tests.
    // TODO: We should eventually have some way of filtering out trivia for
    // tests, so that it can appear in regular dumps.
    return "customCharacterClass(inverted: \(isInverted), \(strippingTriviaShallow.members))"
  }
}

extension AST.CustomCharacterClass.Member: _ASTPrintable {
  public var _dumpBase: String {
    switch self {
    case .custom(let cc): return "\(cc)"
    case .atom(let a): return "\(a)"
    case .range(let r): return "\(r)"
    case .quote(let q): return "\(q)"
    case .trivia(let t): return "\(t)"
    case .setOperation(let lhs, let op, let rhs):
      // TODO: We should eventually have some way of filtering out trivia for
      // tests, so that it can appear in regular dumps.
      return "op \(lhs.filter(\.isSemantic)) \(op.value) \(rhs.filter(\.isSemantic))"
    }
  }
}

extension AST.CustomCharacterClass.Range: _ASTPrintable {
  public var _dumpBase: String {
    "\(lhs)-\(rhs)"
  }
}

extension AST.Atom.BacktrackingDirective: _ASTPrintable {
  public var _dumpBase: String {
    var result = "\(kind.value)"
    if let name = name {
      result += ": \(name.value)"
    }
    return result
  }
}

extension AST.Group.BalancedCapture: _ASTPrintable {
  public var _dumpBase: String {
   "\(name?.value ?? "")-\(priorName.value)"
  }
}

extension AST.AbsentFunction.Kind {
  public var _dumpBase: String {
    switch self {
    case .repeater:
      return "repeater"
    case .expression:
      return "expression"
    case .stopper:
      return "stopper"
    case .clearer:
      return "clearer"
    }
  }
}

extension AST.AbsentFunction {
  public var _dumpBase: String {
    "absent function \(kind._dumpBase)"
  }
}

extension AST.GlobalMatchingOption.Kind: _ASTPrintable {
  public var _dumpBase: String { _canonicalBase }
}

extension AST.GlobalMatchingOption: _ASTPrintable {
  public var _dumpBase: String { "\(kind._dumpBase)" }
}

extension AST.GlobalMatchingOptionSequence: _ASTPrintable {
  public var _dumpBase: String {
    "GlobalMatchingOptionSequence<\(options)>"
  }
}