use rstest::*;
use steel_decimal::{FunctionRegistry, FunctionRegistryBuilder};
use steel::steel_vm::engine::Engine;
use steel::rvals::SteelVal;
use std::collections::HashMap;

#[fixture]
fn fresh_vm() -> Engine {
    Engine::new()
}

// Test basic function registration
#[rstest]
fn test_register_all_functions(mut fresh_vm: Engine) {
    FunctionRegistry::register_all(&mut fresh_vm);
    
    // Test that all major function categories work
    let scripts = vec![
        r#"(decimal-add "1" "2")"#,
        r#"(decimal-pow "2" "3")"#,
        r#"(decimal-sin "0")"#,
        r#"(decimal-gt "5" "3")"#,
        r#"(decimal-abs "-5")"#,
        r#"(decimal-zero)"#,
        r#"(decimal-percentage "100" "10")"#,
        r#"(to-decimal "123.45")"#,
    ];
    
    for script in scripts {
        let result = fresh_vm.compile_and_run_raw_program(script.to_string());
        assert!(result.is_ok(), "Failed to execute: {}", script);
    }
}

// Test selective function registration
#[rstest]
fn test_basic_arithmetic_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(true)
        .advanced_math(false)
        .trigonometric(false)
        .comparison(false)
        .utility(false)
        .constants(false)
        .financial(false)
        .conversion(false)
        .register(&mut fresh_vm);
    
    // Basic arithmetic should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-add "1" "2")"#.to_string());
    assert!(result.is_ok());
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-mul "3" "4")"#.to_string());
    assert!(result.is_ok());
    
    // Note: Advanced math, trig, etc. won't be available but we can't easily test
    // their absence without expecting compilation/runtime errors
}

#[rstest]
fn test_advanced_math_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(false)
        .advanced_math(true)
        .trigonometric(false)
        .comparison(false)
        .utility(false)
        .constants(false)
        .financial(false)
        .conversion(false)
        .register(&mut fresh_vm);
    
    // Advanced math should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-pow "2" "3")"#.to_string());
    assert!(result.is_ok());
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-sqrt "16")"#.to_string());
    assert!(result.is_ok());
}

#[rstest]
fn test_trigonometric_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(false)
        .advanced_math(false)
        .trigonometric(true)
        .comparison(false)
        .utility(false)
        .constants(false)
        .financial(false)
        .conversion(false)
        .register(&mut fresh_vm);
    
    // Trigonometric functions should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-sin "0")"#.to_string());
    assert!(result.is_ok());
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-cos "0")"#.to_string());
    assert!(result.is_ok());
}

#[rstest]
fn test_comparison_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(false)
        .advanced_math(false)
        .trigonometric(false)
        .comparison(true)
        .utility(false)
        .constants(false)
        .financial(false)
        .conversion(false)
        .register(&mut fresh_vm);
    
    // Comparison functions should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-gt "5" "3")"#.to_string());
    assert!(result.is_ok());
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-eq "5" "5")"#.to_string());
    assert!(result.is_ok());
}

#[rstest]
fn test_utility_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(false)
        .advanced_math(false)
        .trigonometric(false)
        .comparison(false)
        .utility(true)
        .constants(false)
        .financial(false)
        .conversion(false)
        .register(&mut fresh_vm);
    
    // Utility functions should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-abs "-5")"#.to_string());
    assert!(result.is_ok());
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-min "3" "5")"#.to_string());
    assert!(result.is_ok());
}

#[rstest]
fn test_constants_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(false)
        .advanced_math(false)
        .trigonometric(false)
        .comparison(false)
        .utility(false)
        .constants(true)
        .financial(false)
        .conversion(false)
        .register(&mut fresh_vm);
    
    // Constants should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-pi)"#.to_string());
    assert!(result.is_ok());
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-zero)"#.to_string());
    assert!(result.is_ok());
}

#[rstest]
fn test_financial_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(false)
        .advanced_math(false)
        .trigonometric(false)
        .comparison(false)
        .utility(false)
        .constants(false)
        .financial(true)
        .conversion(false)
        .register(&mut fresh_vm);
    
    // Financial functions should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-percentage "100" "10")"#.to_string());
    assert!(result.is_ok());
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-compound "1000" "0.05" "1")"#.to_string());
    assert!(result.is_ok());
}

#[rstest]
fn test_conversion_only(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(false)
        .advanced_math(false)
        .trigonometric(false)
        .comparison(false)
        .utility(false)
        .constants(false)
        .financial(false)
        .conversion(true)
        .register(&mut fresh_vm);
    
    // Conversion functions should work
    let result = fresh_vm.compile_and_run_raw_program(r#"(to-decimal "123.45")"#.to_string());
    assert!(result.is_ok());
}

// Test variable registration
#[rstest]
fn test_variable_registration(mut fresh_vm: Engine) {
    let mut variables = HashMap::new();
    variables.insert("x".to_string(), "10.5".to_string());
    variables.insert("y".to_string(), "20.3".to_string());
    variables.insert("name".to_string(), "test_value".to_string());
    
    FunctionRegistryBuilder::new()
        .basic_arithmetic(true)
        .with_variables(variables)
        .register(&mut fresh_vm);
    
    // Test getting variables
    let result = fresh_vm.compile_and_run_raw_program(r#"(get-var "x")"#.to_string()).unwrap();
    assert_eq!(result.len(), 1);
    if let SteelVal::StringV(s) = &result[0] {
        assert_eq!(s.to_string(), "10.5");
    }
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(get-var "y")"#.to_string()).unwrap();
    assert_eq!(result.len(), 1);
    if let SteelVal::StringV(s) = &result[0] {
        assert_eq!(s.to_string(), "20.3");
    }
    
    // Test checking if variables exist
    let result = fresh_vm.compile_and_run_raw_program(r#"(has-var? "x")"#.to_string()).unwrap();
    assert_eq!(result.len(), 1);
    if let SteelVal::BoolV(b) = &result[0] {
        assert!(b);
    }
    
    let result = fresh_vm.compile_and_run_raw_program(r#"(has-var? "nonexistent")"#.to_string()).unwrap();
    assert_eq!(result.len(), 1);
    if let SteelVal::BoolV(b) = &result[0] {
        assert!(!b);
    }
    
    // Test using variables in arithmetic
    let result = fresh_vm.compile_and_run_raw_program(r#"(decimal-add (get-var "x") (get-var "y"))"#.to_string()).unwrap();
    assert_eq!(result.len(), 1);
    if let SteelVal::StringV(s) = &result[0] {
        assert_eq!(s.to_string(), "30.8");
    }
}

// Test error handling in variable access
#[rstest]
fn test_variable_error_handling(mut fresh_vm: Engine) {
    let variables = HashMap::new(); // Empty variables
    
    FunctionRegistryBuilder::new()
        .with_variables(variables)
        .register(&mut fresh_vm);
    
    // Should get an error for non-existent variable
    let result = fresh_vm.compile_and_run_raw_program(r#"(get-var "nonexistent")"#.to_string());
    // The function should return an error, but Steel might handle it differently
    // This test ensures the function is registered and callable
    assert!(result.is_ok() || result.is_err()); // Either way is fine, just shouldn't panic
}

// Test function name listing
#[rstest]
fn test_function_names() {
    let names = FunctionRegistry::get_function_names();
    
    // Check that all expected function categories are present
    assert!(names.contains(&"decimal-add"));
    assert!(names.contains(&"decimal-pow"));
    assert!(names.contains(&"decimal-sin"));
    assert!(names.contains(&"decimal-gt"));
    assert!(names.contains(&"decimal-abs"));
    assert!(names.contains(&"decimal-pi"));
    assert!(names.contains(&"decimal-percentage"));
    assert!(names.contains(&"to-decimal"));
    assert!(names.contains(&"get-var"));
    assert!(names.contains(&"has-var?"));
    
    // Check total count is reasonable
    assert!(names.len() >= 25); // Should have at least 25 functions
}

// Test builder pattern combinations
#[rstest]
fn test_builder_combinations(mut fresh_vm: Engine) {
    FunctionRegistryBuilder::new()
        .basic_arithmetic(true)
        .comparison(true)
        .constants(true)
        .register(&mut fresh_vm);
    
    // Should be able to use arithmetic, comparison, and constants
    let result = fresh_vm.compile_and_run_raw_program(
        r#"(decimal-gt (decimal-add "1" "2") (decimal-zero))"#.to_string()
    ).unwrap();
    
    assert_eq!(result.len(), 1);
    if let SteelVal::BoolV(b) = &result[0] {
        assert!(b); // 3 > 0 should be true
    }
}

// Test default builder behavior
#[rstest]
fn test_builder_defaults(mut fresh_vm: Engine) {
    // Default should include everything
    FunctionRegistryBuilder::new().register(&mut fresh_vm);
    
    // Should be able to use any function
    let scripts = vec![
        r#"(decimal-add "1" "2")"#,
        r#"(decimal-pow "2" "3")"#,
        r#"(decimal-sin "0")"#,
        r#"(decimal-gt "5" "3")"#,
        r#"(decimal-abs "-5")"#,
        r#"(decimal-pi)"#,
        r#"(decimal-percentage "100" "10")"#,
        r#"(to-decimal "123.45")"#,
    ];
    
    for script in scripts {
        let result = fresh_vm.compile_and_run_raw_program(script.to_string());
        assert!(result.is_ok(), "Failed to execute with default builder: {}", script);
    }
}

// Test multiple variable sets
#[rstest]
fn test_multiple_variable_registration(mut fresh_vm: Engine) {
    let mut variables1 = HashMap::new();
    variables1.insert("a".to_string(), "1".to_string());
    variables1.insert("b".to_string(), "2".to_string());
    
    // Register first set
    FunctionRegistryBuilder::new()
        .with_variables(variables1)
        .register(&mut fresh_vm);
    
    // Test first set works
    let result = fresh_vm.compile_and_run_raw_program(r#"(get-var "a")"#.to_string()).unwrap();
    if let SteelVal::StringV(s) = &result[0] {
        assert_eq!(s.to_string(), "1");
    }
    
    // Note: In a real scenario, you probably wouldn't register variables twice
    // This is just testing that the registration mechanism works
}