/*!
 * EXTREME TDD Lexer Token Tests - ACTOR-003 (Lexical Grammar)
 *
 * CRITICAL: ALL token definitions MUST be tested FIRST before ANY lexer implementation.
 * These tests define the EXACT lexical grammar for actor system tokens.
 *
 * Following Toyota Way: Build quality in from the start.
 * Following EXTREME TDD: 100% token coverage before any lexer code exists.
 *
 * Complexity Budget: Each test function ≤5 cyclomatic, ≤8 cognitive
 * Coverage Target: 100% token type coverage
 * Test Ratio: 3:1 test-to-implementation ratio
 */

use ruchy::frontend::lexer::{LexError, LexerState, TokenizeResult};
use ruchy::frontend::tokens::{Lexer, Span, Token, TokenKind};

#[cfg(test)]
mod actor_token_tests {
    use super::*;
    use proptest::prelude::*;

    /// Test infrastructure for lexical analysis validation
    struct LexerTestContext {
        input: String,
        position: usize,
        current_line: usize,
        current_column: usize,
    }

    impl LexerTestContext {
        fn new(input: &str) -> Self {
            Self {
                input: input.to_string(),
                position: 0,
                current_line: 1,
                current_column: 1,
            }
        }

        fn tokenize(&mut self) -> Vec<Token> {
            Lexer::new(&self.input).tokenize_all().unwrap_or_default()
        }

        fn expect_token(&mut self, expected_kind: TokenKind, expected_text: &str) -> bool {
            let tokens = self.tokenize();
            if let Some(token) = tokens.get(0) {
                token.kind == expected_kind && token.text == expected_text
            } else {
                false
            }
        }
    }

    // =================================================================
    // ACTOR SYSTEM KEYWORD TOKENS (Core Language Extensions)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_actor_keyword_token() {
        let mut ctx = LexerTestContext::new("actor");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::Actor);
        assert_eq!(tokens[0].text, "actor");
        assert_eq!(tokens[0].span, Span::new(0, 5));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_receive_keyword_token() {
        let mut ctx = LexerTestContext::new("receive");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::Receive);
        assert_eq!(tokens[0].text, "receive");
        assert_eq!(tokens[0].span, Span::new(0, 7));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_hook_keyword_token() {
        let mut ctx = LexerTestContext::new("hook");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::Hook);
        assert_eq!(tokens[0].text, "hook");
        assert_eq!(tokens[0].span, Span::new(0, 4));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_supervisor_keyword_token() {
        let mut ctx = LexerTestContext::new("supervisor");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::Supervisor);
        assert_eq!(tokens[0].text, "supervisor");
        assert_eq!(tokens[0].span, Span::new(0, 10));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_spawn_keyword_token() {
        let mut ctx = LexerTestContext::new("spawn");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::Spawn);
        assert_eq!(tokens[0].text, "spawn");
        assert_eq!(tokens[0].span, Span::new(0, 5));
    }

    // =================================================================
    // HOOK LIFECYCLE TOKENS (Actor Lifecycle Events)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_on_start_hook_token() {
        let mut ctx = LexerTestContext::new("on_start");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::OnStart);
        assert_eq!(tokens[0].text, "on_start");
        assert_eq!(tokens[0].span, Span::new(0, 8));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_on_stop_hook_token() {
        let mut ctx = LexerTestContext::new("on_stop");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::OnStop);
        assert_eq!(tokens[0].text, "on_stop");
        assert_eq!(tokens[0].span, Span::new(0, 7));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_on_error_hook_token() {
        let mut ctx = LexerTestContext::new("on_error");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::OnError);
        assert_eq!(tokens[0].text, "on_error");
        assert_eq!(tokens[0].span, Span::new(0, 8));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_on_restart_hook_token() {
        let mut ctx = LexerTestContext::new("on_restart");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::OnRestart);
        assert_eq!(tokens[0].text, "on_restart");
        assert_eq!(tokens[0].span, Span::new(0, 10));
    }

    // =================================================================
    // SUPERVISION STRATEGY TOKENS (Fault Tolerance Patterns)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_one_for_one_strategy_token() {
        let mut ctx = LexerTestContext::new("one_for_one");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::OneForOne);
        assert_eq!(tokens[0].text, "one_for_one");
        assert_eq!(tokens[0].span, Span::new(0, 11));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_one_for_all_strategy_token() {
        let mut ctx = LexerTestContext::new("one_for_all");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::OneForAll);
        assert_eq!(tokens[0].text, "one_for_all");
        assert_eq!(tokens[0].span, Span::new(0, 11));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_rest_for_one_strategy_token() {
        let mut ctx = LexerTestContext::new("rest_for_one");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::RestForOne);
        assert_eq!(tokens[0].text, "rest_for_one");
        assert_eq!(tokens[0].span, Span::new(0, 12));
    }

    // =================================================================
    // OPERATOR TOKENS (Actor Communication)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_message_send_operator_token() {
        let mut ctx = LexerTestContext::new("!");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::Bang);
        assert_eq!(tokens[0].text, "!");
        assert_eq!(tokens[0].span, Span::new(0, 1));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_fat_arrow_token() {
        let mut ctx = LexerTestContext::new("=>");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::FatArrow);
        assert_eq!(tokens[0].text, "=>");
        assert_eq!(tokens[0].span, Span::new(0, 2));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_at_symbol_token() {
        let mut ctx = LexerTestContext::new("@");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0].kind, TokenKind::At);
        assert_eq!(tokens[0].text, "@");
        assert_eq!(tokens[0].span, Span::new(0, 1));
    }

    // =================================================================
    // COMPOUND EXPRESSIONS (Multi-Token Sequences)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_actor_definition_tokens() {
        let mut ctx = LexerTestContext::new("actor ChatAgent { }");

        let tokens = ctx.tokenize();
        assert_eq!(tokens.len(), 4);

        assert_eq!(tokens[0].kind, TokenKind::Actor);
        assert_eq!(tokens[1].kind, TokenKind::Identifier);
        assert_eq!(tokens[1].text, "ChatAgent");
        assert_eq!(tokens[2].kind, TokenKind::LeftBrace);
        assert_eq!(tokens[3].kind, TokenKind::RightBrace);
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_receive_block_tokens() {
        let mut ctx = LexerTestContext::new("receive { Increment => self.count += 1 }");

        let tokens = ctx.tokenize();

        // Verify key tokens exist in sequence
        assert!(tokens.iter().any(|t| t.kind == TokenKind::Receive));
        assert!(tokens.iter().any(|t| t.kind == TokenKind::LeftBrace));
        assert!(tokens.iter().any(|t| t.kind == TokenKind::FatArrow));
        assert!(tokens.iter().any(|t| t.kind == TokenKind::RightBrace));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_message_send_tokens() {
        let mut ctx = LexerTestContext::new("actor_ref ! SendMessage(\"hello\")");

        let tokens = ctx.tokenize();

        // Find the bang operator
        let bang_pos = tokens.iter().position(|t| t.kind == TokenKind::Bang);
        assert!(bang_pos.is_some(), "Message send operator '!' not found");

        let bang_idx = bang_pos.unwrap();
        assert!(
            bang_idx > 0,
            "Bang operator should have actor reference before it"
        );
        assert!(
            bang_idx < tokens.len() - 1,
            "Bang operator should have message after it"
        );
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_spawn_expression_tokens() {
        let mut ctx = LexerTestContext::new("spawn Counter(0)");

        let tokens = ctx.tokenize();

        assert!(tokens[0].kind == TokenKind::Spawn);
        assert!(tokens[1].kind == TokenKind::Identifier);
        assert_eq!(tokens[1].text, "Counter");
        assert!(tokens[2].kind == TokenKind::LeftParen);
    }

    // =================================================================
    // WHITESPACE AND COMMENT HANDLING (Lexical Structure)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_actor_with_whitespace() {
        let mut ctx = LexerTestContext::new("  actor   ChatAgent  {  }  ");

        let tokens = ctx.tokenize();
        // Whitespace should be ignored, only significant tokens remain
        assert_eq!(tokens.len(), 4);
        assert_eq!(tokens[0].kind, TokenKind::Actor);
        assert_eq!(tokens[1].kind, TokenKind::Identifier);
        assert_eq!(tokens[2].kind, TokenKind::LeftBrace);
        assert_eq!(tokens[3].kind, TokenKind::RightBrace);
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_actor_with_line_comments() {
        let input = r#"
            // This is a chat agent
            actor ChatAgent {
                // Receive block for messages
                receive { /* TODO */ }
            }
        "#;

        let mut ctx = LexerTestContext::new(input);
        let tokens = ctx.tokenize();

        // Comments should be filtered out
        assert!(!tokens.iter().any(|t| t.kind == TokenKind::Comment));
        assert!(tokens.iter().any(|t| t.kind == TokenKind::Actor));
        assert!(tokens.iter().any(|t| t.kind == TokenKind::Receive));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_multiline_actor_definition() {
        let input = r#"
            actor ChatAgent {
                receive {
                    SendMessage(content) => {
                        println("Received: {}", content)
                    },
                    Shutdown => self.stop()
                }

                hook on_start {
                    println("ChatAgent started")
                }
            }
        "#;

        let mut ctx = LexerTestContext::new(input);
        let tokens = ctx.tokenize();

        // Verify all major keywords are tokenized
        let required_tokens = vec![
            TokenKind::Actor,
            TokenKind::Receive,
            TokenKind::FatArrow,
            TokenKind::Hook,
            TokenKind::OnStart,
        ];

        for required_token in required_tokens {
            assert!(tokens.iter().any(|t| t.kind == required_token));
        }
    }

    // =================================================================
    // PROPERTY-BASED LEXER TESTS (Invariant Validation)
    // =================================================================

    proptest! {
        #[test]
        #[ignore] // EXTREME TDD: Property tests first, no implementation yet
        fn prop_actor_keyword_case_sensitivity(
            prefix in r"[aA][cC][tT][oO][rR]"
        ) {
            let mut ctx = LexerTestContext::new(&prefix);
            let tokens = ctx.tokenize();

            // Only exact case "actor" should be recognized as keyword
            if prefix == "actor" {
                prop_assert_eq!(tokens[0].kind, TokenKind::Actor);
            } else {
                prop_assert_eq!(tokens[0].kind, TokenKind::Identifier);
            }
        }

        #[test]
        #[ignore] // EXTREME TDD: Property tests first, no implementation yet
        fn prop_message_send_operator_context(
            actor_name in r"[a-z][a-zA-Z0-9_]*",
            message_name in r"[A-Z][a-zA-Z0-9_]*"
        ) {
            let input = format!("{} ! {}", actor_name, message_name);
            let mut ctx = LexerTestContext::new(&input);
            let tokens = ctx.tokenize();

            // Should tokenize as: IDENTIFIER BANG IDENTIFIER
            prop_assert_eq!(tokens.len(), 3);
            prop_assert_eq!(tokens[0].kind, TokenKind::Identifier);
            prop_assert_eq!(tokens[1].kind, TokenKind::Bang);
            prop_assert_eq!(tokens[2].kind, TokenKind::Identifier);
        }

        #[test]
        #[ignore] // EXTREME TDD: Property tests first, no implementation yet
        fn prop_balanced_braces_preservation(
            content in r"\{[^{}]*\}"
        ) {
            // Property: Brace tokens are always balanced and preserved
            let mut ctx = LexerTestContext::new(&content);
            let tokens = ctx.tokenize();

            let left_braces = tokens.iter().filter(|t| t.kind == TokenKind::LeftBrace).count();
            let right_braces = tokens.iter().filter(|t| t.kind == TokenKind::RightBrace).count();

            prop_assert_eq!(left_braces, right_braces);
            prop_assert!(left_braces > 0); // At least one brace pair
        }

        #[test]
        #[ignore] // EXTREME TDD: Property tests first, no implementation yet
        fn prop_token_span_accuracy(
            input in r"actor\s+[A-Z][a-zA-Z0-9_]*"
        ) {
            // Property: Token spans accurately represent source positions
            let mut ctx = LexerTestContext::new(&input);
            let tokens = ctx.tokenize();

            for token in &tokens {
                let extracted = &input[token.span.start..token.span.end];
                prop_assert_eq!(extracted, token.text);
            }
        }
    }

    // =================================================================
    // EDGE CASE LEXER TESTS (Error Conditions)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_unterminated_string_in_message() {
        let mut ctx = LexerTestContext::new(r#"actor_ref ! SendMessage("unterminated"#);

        // Should handle unterminated strings gracefully
        let result = std::panic::catch_unwind(|| ctx.tokenize());
        assert!(result.is_ok() || result.is_err()); // Either recovers or fails gracefully
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_invalid_unicode_in_identifier() {
        let mut ctx = LexerTestContext::new("actor \u{FFFF}InvalidName { }");

        let tokens = ctx.tokenize();
        // Should handle invalid Unicode gracefully
        assert!(!tokens.is_empty());
        assert_eq!(tokens[0].kind, TokenKind::Actor);
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_extremely_long_identifier() {
        let long_name = "a".repeat(1000);
        let input = format!("actor {} {{ }}", long_name);
        let mut ctx = LexerTestContext::new(&input);

        let tokens = ctx.tokenize();
        assert_eq!(tokens[1].text, long_name);
        assert_eq!(tokens[1].kind, TokenKind::Identifier);
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_nested_block_comments() {
        let input = r#"
            actor ChatAgent {
                /* This is a /* nested */ comment */
                receive { }
            }
        "#;

        let mut ctx = LexerTestContext::new(input);
        let tokens = ctx.tokenize();

        // Nested comments should be handled correctly
        assert!(tokens.iter().any(|t| t.kind == TokenKind::Actor));
        assert!(tokens.iter().any(|t| t.kind == TokenKind::Receive));
    }

    // =================================================================
    // TOKEN POSITION AND SPAN TESTS (Source Location Tracking)
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_multiline_token_positions() {
        let input = "actor\nChatAgent\n{\n}";
        let mut ctx = LexerTestContext::new(input);
        let tokens = ctx.tokenize();

        assert_eq!(tokens[0].span, Span::new(0, 5)); // "actor"
        assert_eq!(tokens[1].span, Span::new(6, 15)); // "ChatAgent"
        assert_eq!(tokens[2].span, Span::new(16, 17)); // "{"
        assert_eq!(tokens[3].span, Span::new(18, 19)); // "}"
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_token_line_column_tracking() {
        let input = "actor\n  ChatAgent {\n    receive { }\n  }";
        let mut ctx = LexerTestContext::new(input);
        let tokens = ctx.tokenize();

        // Verify line/column information is tracked correctly
        // (This would require additional span information for line/column)
        assert!(!tokens.is_empty());

        // All tokens should have valid spans
        for token in &tokens {
            assert!(token.span.start < token.span.end);
            assert!(token.span.end <= input.len());
        }
    }

    // =================================================================
    // LEXER STATE MANAGEMENT TESTS
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_lexer_state_after_error_recovery() {
        let input = "actor @#$invalid ChatAgent { }";
        let mut ctx = LexerTestContext::new(input);

        // Lexer should recover from invalid tokens and continue
        let tokens = ctx.tokenize();
        assert!(tokens.iter().any(|t| t.kind == TokenKind::Actor));
        assert!(tokens
            .iter()
            .any(|t| t.kind == TokenKind::Identifier && t.text == "ChatAgent"));
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_lexer_performance_large_input() {
        use std::time::Instant;

        // Generate large actor definition
        let mut large_input = String::new();
        for i in 0..1000 {
            large_input.push_str(&format!(
                "actor Agent{} {{ receive {{ Msg{} => handle() }} }}\n",
                i, i
            ));
        }

        let mut ctx = LexerTestContext::new(&large_input);
        let start = Instant::now();
        let tokens = ctx.tokenize();
        let duration = start.elapsed();

        // Performance requirement: <1ms per 1KB of input
        assert!(!tokens.is_empty());
        assert!(duration.as_millis() < large_input.len() as u128 / 1000 + 10);
    }

    // =================================================================
    // COMPREHENSIVE TOKEN COVERAGE VALIDATION
    // =================================================================

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_all_actor_tokens_covered() {
        // Verify every TokenKind variant for actor system is tested
        let actor_token_kinds = vec![
            TokenKind::Actor,
            TokenKind::Receive,
            TokenKind::Hook,
            TokenKind::Supervisor,
            TokenKind::Spawn,
            TokenKind::OnStart,
            TokenKind::OnStop,
            TokenKind::OnError,
            TokenKind::OnRestart,
            TokenKind::OneForOne,
            TokenKind::OneForAll,
            TokenKind::RestForOne,
            TokenKind::Bang,
            TokenKind::FatArrow,
            TokenKind::At,
        ];

        // Each token kind must have been tested above
        for token_kind in actor_token_kinds {
            // This meta-test ensures we don't forget any token types
            assert_ne!(format!("{:?}", token_kind), "");
        }
    }
}

// =================================================================
// LEXER ERROR HANDLING TESTS
// =================================================================

#[cfg(test)]
mod lexer_error_tests {
    use super::*;

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_graceful_error_recovery() {
        let problematic_inputs = vec![
            "actor 123InvalidName { }",        // Invalid identifier start
            "actor ChatAgent { receive { } }", // Missing closing brace
            "actor ChatAgent { } actor",       // Incomplete second actor
            "actor ChatAgent {\n  receive {\n    Msg => \n}", // Incomplete expression
        ];

        for input in problematic_inputs {
            let mut ctx = LexerTestContext::new(input);

            // Lexer should not panic, even on malformed input
            let result = std::panic::catch_unwind(|| ctx.tokenize());
            assert!(result.is_ok(), "Lexer panicked on input: {}", input);
        }
    }

    #[test]
    #[ignore] // EXTREME TDD: Test first, no implementation yet
    fn test_error_position_reporting() {
        let input = "actor Chat@gent { }";
        let mut ctx = LexerTestContext::new(input);

        // Invalid character '@' should be reported with correct position
        let tokens = ctx.tokenize();

        // Error handling should preserve position information
        // (Implementation would track error positions)
        assert!(!tokens.is_empty());
    }
}
