// p4rse, Copyright 2026, Will Hawkins
//
// This file is part of p4rse.
//
// This file 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/>.

import Common
import P4Compiler

public struct TextSerializer {
  public init() {}
}

public struct TextSerializerContext {
  public let serialized: String

  public init(_ serialized: String = "") {
    self.serialized = serialized
  }

  public func append(_ a: String) -> TextSerializerContext {
    return TextSerializerContext(self.serialized + a)
  }
}

extension TextSerializer: ASTVisitor<TextSerializerContext> {
  public func visit(
    node: P4Compiler.AST.BinaryOperatorExpression, driver: P4Compiler.ASTVisitorDriver,
    context: TextSerializerContext
  ) -> Common.Result<TextSerializerContext> {
    return .Ok(context.append("Binary Operator Expression"))

  }

  public func visit(
    node: P4Compiler.AST.Literal, driver: P4Compiler.ASTVisitorDriver,
    context: TextSerializerContext
  ) -> Common.Result<TextSerializerContext> {
    return .Ok(context.append("Literal Expression"))
  }

  public func visit(
    node: P4Compiler.AST.Identifier, driver: P4Compiler.ASTVisitorDriver,
    context: TextSerializerContext
  ) -> Common.Result<TextSerializerContext> {
    return .Ok(context.append("Identifier Expression"))
  }

  public func visit(
    node: P4Compiler.AST.Parser, driver: P4Compiler.ASTVisitorDriver, context: TextSerializerContext
  ) -> Common.Result<TextSerializerContext> {
    var context = context.append("Identifier Expression")
    for s in node.states.states {
      switch driver.visit(state: s, visitor: self, context: context) {
      case .Ok(let c): context = c
      case .Error(let e): return .Error(e)
      }
    }

    return .Ok(context)
  }

  public func visit(
    node: P4Compiler.AST.ParserStateDirectTransition, driver: P4Compiler.ASTVisitorDriver,
    context: TextSerializerContext
  ) -> Common.Result<TextSerializerContext> {
    return .Ok(context.append("State: Direct Transition"))
  }

  public func visit(
    node: P4Compiler.AST.ParserStateNoTransition, driver: P4Compiler.ASTVisitorDriver,
    context: TextSerializerContext
  ) -> Common.Result<TextSerializerContext> {
    return .Ok(context.append("State: No Transition"))
  }

  public func visit(
    node: P4Compiler.AST.ParserStateSelectTransition, driver: P4Compiler.ASTVisitorDriver,
    context: TextSerializerContext
  ) -> Common.Result<TextSerializerContext> {
    return .Ok(context.append("State: Direct Transition"))
  }

}