// 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 Foundation
import Lang
import Macros
import Runtime
import SwiftTreeSitter
import Testing
import TreeSitter
import TreeSitterP4

@testable import Parser

@Test func test_simple_runtime() async throws {
  let simple_parser_declaration = """
    parser main_parser() {
       state start {
           true;
           transition accept;
       }
    };
    """

  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
  #expect(#RequireOkResult(Runtime.ParserRuntime.create(program: program)))

  let runtime = try #UseOkResult(Runtime.ParserRuntime.create(program: program))

  guard case Common.Result.Ok(let (state_result, _)) = runtime.run(input: Packet())
  else {
    assert(false)
  }

  // We should be in the accept state.
  #expect(state_result == Lang.accept)
}

@Test func test_simple_runtime_to_accept() async throws {
  let simple_parser_declaration = """
    parser main_parser() {
       state start {
           true;
           transition reject;
       }
    };
    """

  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
  #expect(#RequireOkResult(Runtime.ParserRuntime.create(program: program)))

  let runtime = try #UseOkResult(Runtime.ParserRuntime.create(program: program))

  guard case Common.Result.Ok(let (state_result, _)) = runtime.run(input: Packet())
  else {
    assert(false)
  }

  // We should be in the accept state.
  #expect(state_result == Lang.reject)
}


@Test func test_simple_runtime_no_start_state() async throws {
  let simple_parser_declaration = """
    parser main_parser() {
       state tart {
           true;
           transition reject;
       }
    };
    """

  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
  #expect(
    #RequireErrorResult<ParserRuntime>(
      Error(withMessage: "Could not find the start state"),
      Runtime.ParserRuntime.create(program: program)))
}

@Test func test_simple_local_element_variable_declaration() async throws {
  let simple_parser_declaration = """
    parser main_parser() {
       state start {
           bool b = false;
           string s = "testing";
           true;
           false;
           transition reject;
       }
    };
    """

  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
  let runtime = try #UseOkResult(Runtime.ParserRuntime.create(program: program))

  // This seems awkward to me!
  // TODO: Is there a better way?
  guard case Common.Result.Ok(let (state_result, execution_result)) = runtime.run(input: Packet())
  else {
    assert(false)
  }

  // There should be 1 scope.
  #expect(execution_result.scopes.count == 1)

  guard let scope = execution_result.scopes.current else {
    assert(false)
  }

  // We should be in the accept state.
  #expect(state_result == Lang.reject)

  // There are two variables declared.
  #expect(scope.count == 2)

  // Check the names/values of the variables in scope.
  let b = try #require(scope.lookup(identifier: Identifier(name: "b")))
  let s = try #require(scope.lookup(identifier: Identifier(name: "s")))
  #expect(b.value_type.eq(rhs: P4BooleanValue(withValue: false)))
  #expect(s.value_type.eq(rhs: P4StringValue(withValue: "\"testing\"")))
}

@Test func test_simple_parser_with_transition_select_expression() async throws {
  let simple_parser_declaration = """
      parser main_parser() {
        state start {
          transition select (true) {
            false: reject;
            true: accept;
          };
        }
      };
    """

  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
  #expect(#RequireOkResult(program.find_parser(withName: Identifier(name: "main_parser"))))
  let parser = try #UseOkResult(program.find_parser(withName: Identifier(name: "main_parser")))

  #expect(parser.states.count() == 1)

  let runtime = try #UseOkResult(Runtime.ParserRuntime.create(program: program))

  guard case Common.Result.Ok(let (state_result, _)) = runtime.run(input: Packet())
  else {
    assert(false)
  }
  #expect(state_result == Lang.accept)
}

@Test func test_simple_parser_with_transition_select_expression_to_reject() async throws {
  let simple_parser_declaration = """
      parser main_parser() {
        state start {
          transition select (false) {
            false: reject;
            true: accept;
          };
        }
      };
    """

  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
  #expect(#RequireOkResult(program.find_parser(withName: Identifier(name: "main_parser"))))
  let parser = try #UseOkResult(program.find_parser(withName: Identifier(name: "main_parser")))

  #expect(parser.states.count() == 1)

  let runtime = try #UseOkResult(Runtime.ParserRuntime.create(program: program))

  guard case Common.Result.Ok(let (state_result, _)) = runtime.run(input: Packet())
  else {
    assert(false)
  }
  #expect(state_result == Lang.reject)
}