// Characterization tests for TUI App behavior
// These tests capture current behavior before architectural refactoring
// They ensure that the refactoring doesn't change application behavior

// NOTE: Due to module visibility, we'll test the public interfaces rather than internal state
// This is actually better practice - testing public behavior rather than implementation details

use mermaid_cli::agents::AgentAction;
use mermaid_cli::tui::{AppState, GenerationStatus};

// ===== APP STATE ENUM TESTS =====

#[test]
fn test_app_state_is_generating_method() {
    let state = AppState::Idle;
    assert!(!state.is_generating());
    assert!(state.is_idle());

    let generating_state = AppState::Generating {
        status: GenerationStatus::Thinking,
        start_time: std::time::Instant::now(),
        tokens_received: 0,
        abort_handle: None,
        response_buffer: String::new(),
    };
    assert!(generating_state.is_generating());
    assert!(!generating_state.is_idle());
}

#[test]
fn test_app_state_generation_status_method() {
    let idle_state = AppState::Idle;
    assert_eq!(idle_state.generation_status(), None);

    let generating_state = AppState::Generating {
        status: GenerationStatus::Streaming,
        start_time: std::time::Instant::now(),
        tokens_received: 42,
        abort_handle: None,
        response_buffer: String::new(),
    };
    assert_eq!(
        generating_state.generation_status(),
        Some(GenerationStatus::Streaming)
    );
}

#[test]
fn test_generation_status_display_text() {
    assert_eq!(GenerationStatus::Idle.display_text(), "Idle");
    assert_eq!(GenerationStatus::Sending.display_text(), "Sending");
    assert_eq!(GenerationStatus::Thinking.display_text(), "Thinking");
    assert_eq!(GenerationStatus::Streaming.display_text(), "Streaming");
}

#[test]
fn test_app_state_variants_are_distinct() {
    let idle = AppState::Idle;
    let generating = AppState::Generating {
        status: GenerationStatus::Thinking,
        start_time: std::time::Instant::now(),
        tokens_received: 0,
        abort_handle: None,
        response_buffer: String::new(),
    };

    // These should be different variants
    assert!(matches!(idle, AppState::Idle));
    assert!(matches!(generating, AppState::Generating { .. }));
    assert!(!matches!(idle, AppState::Generating { .. }));
    assert!(!matches!(generating, AppState::Idle));
}

// ===== STATE TRANSITION CHARACTERIZATION =====
// These tests document the expected state transitions

#[test]
fn test_state_transition_idle_to_generating() {
    // Initially idle
    let mut state = AppState::Idle;
    assert!(state.is_idle());

    // Transition to generating
    state = AppState::Generating {
        status: GenerationStatus::Thinking,
        start_time: std::time::Instant::now(),
        tokens_received: 0,
        abort_handle: None,
        response_buffer: String::new(),
    };

    // Verify transition
    assert!(!state.is_idle());
    assert!(state.is_generating());
    assert_eq!(state.generation_status(), Some(GenerationStatus::Thinking));
}

#[test]
fn test_state_transition_generating_to_idle() {
    // Start generating
    let mut state = AppState::Generating {
        status: GenerationStatus::Streaming,
        start_time: std::time::Instant::now(),
        tokens_received: 100,
        abort_handle: None,
        response_buffer: String::new(),
    };
    assert!(state.is_generating());

    // Finish and return to idle
    state = AppState::Idle;

    // Verify transition
    assert!(!state.is_generating());
    assert!(state.is_idle());
    assert_eq!(state.generation_status(), None);
}

#[test]
fn test_generation_status_can_be_updated() {
    let mut state = AppState::Generating {
        status: GenerationStatus::Sending,
        start_time: std::time::Instant::now(),
        tokens_received: 0,
        abort_handle: None,
        response_buffer: String::new(),
    };

    // Verify initial status
    assert_eq!(state.generation_status(), Some(GenerationStatus::Sending));

    // Update status (simulating what would happen in the app)
    if let AppState::Generating { status, .. } = &mut state {
        *status = GenerationStatus::Streaming;
    }

    // Verify updated status
    assert_eq!(state.generation_status(), Some(GenerationStatus::Streaming));
}

#[test]
fn test_tokens_received_can_be_incremented() {
    let mut state = AppState::Generating {
        status: GenerationStatus::Streaming,
        start_time: std::time::Instant::now(),
        tokens_received: 0,
        abort_handle: None,
        response_buffer: String::new(),
    };

    // Increment tokens (simulating streaming)
    if let AppState::Generating {
        tokens_received, ..
    } = &mut state
    {
        *tokens_received += 10;
    }

    // Verify increment
    if let AppState::Generating {
        tokens_received, ..
    } = state
    {
        assert_eq!(tokens_received, 10);
    }
}

// ===== MESSAGE ROLE TESTS =====

#[test]
fn test_message_roles_exist() {
    use mermaid_cli::models::MessageRole;

    // Verify all roles can be created
    let user = MessageRole::User;
    let assistant = MessageRole::Assistant;
    let system = MessageRole::System;

    assert!(matches!(user, MessageRole::User));
    assert!(matches!(assistant, MessageRole::Assistant));
    assert!(matches!(system, MessageRole::System));
}

// ===== AGENT ACTION TESTS =====

#[test]
fn test_agent_actions_can_be_created() {
    let read_file = AgentAction::ReadFile {
        paths: vec!["test.rs".to_string()],
    };

    let write_file = AgentAction::WriteFile {
        path: "output.txt".to_string(),
        content: "Hello, world!".to_string(),
    };

    let execute_command = AgentAction::ExecuteCommand {
        command: "ls -la".to_string(),
        working_dir: None,
        timeout: None,
    };

    // Verify actions can be pattern matched
    assert!(matches!(read_file, AgentAction::ReadFile { .. }));
    assert!(matches!(write_file, AgentAction::WriteFile { .. }));
    assert!(matches!(
        execute_command,
        AgentAction::ExecuteCommand { .. }
    ));
}

#[test]
fn test_agent_actions_can_be_cloned() {
    let action = AgentAction::ReadFile {
        paths: vec!["test.rs".to_string()],
    };

    let cloned = action.clone();

    // Verify clone works
    if let (AgentAction::ReadFile { paths: p1 }, AgentAction::ReadFile { paths: p2 }) =
        (&action, &cloned)
    {
        assert_eq!(p1, p2);
    }
}

// ===== DOCUMENTATION OF EXPECTED BEHAVIORS =====

#[test]
fn test_characterization_app_state_must_match_flags() {
    // CRITICAL CHARACTERIZATION TEST
    // This test documents that when is_generating=true, app_state should be AppState::Generating
    // And when is_generating=false, app_state should NOT be AppState::Generating
    //
    // During refactoring, we will eliminate the boolean flags and use ONLY AppState
    // These tests ensure we don't introduce bugs during that migration
    //
    // Expected behavior BEFORE refactoring:
    // - App has both: is_generating: bool AND app_state: AppState
    // - They should ALWAYS be in sync
    // - is_generating == true IFF app_state matches Generating
    //
    // Expected behavior AFTER refactoring:
    // - App has ONLY: app_state: AppState
    // - is_generating is replaced by app_state.is_generating()
    // - All code uses app_state.is_generating() instead of the flag

    let idle = AppState::Idle;
    let generating = AppState::Generating {
        status: GenerationStatus::Thinking,
        start_time: std::time::Instant::now(),
        tokens_received: 0,
        abort_handle: None,
        response_buffer: String::new(),
    };

    // Verify the convenience methods that replace the flags
    assert_eq!(idle.is_generating(), false);
    assert_eq!(generating.is_generating(), true);
}
