//! Task execution with retry logic for G3 CLI.

use g3_core::error_handling::{calculate_retry_delay, classify_error, ErrorType, RecoverableError};
use g3_core::ui_writer::UiWriter;
use g3_core::Agent;
use tokio_util::sync::CancellationToken;
use tracing::error;

use crate::simple_output::SimpleOutput;

/// Maximum number of retry attempts for recoverable errors
const MAX_RETRIES: u32 = 3;

/// Get a human-readable name for a recoverable error type.
fn recoverable_error_name(err: &RecoverableError) -> &'static str {
    match err {
        RecoverableError::RateLimit => "Rate limit",
        RecoverableError::ServerError => "Server error",
        RecoverableError::NetworkError => "Network error",
        RecoverableError::Timeout => "Timeout",
        RecoverableError::ModelBusy => "Model busy",
        RecoverableError::TokenLimit => "Token limit",
        RecoverableError::ContextLengthExceeded => "Context length",
    }
}

/// Execute a task with retry logic for recoverable errors.
pub async fn execute_task_with_retry<W: UiWriter>(
    agent: &mut Agent<W>,
    input: &str,
    show_prompt: bool,
    show_code: bool,
    output: &SimpleOutput,
) {
    let mut attempt = 0;

    output.print("🤔 Thinking...");

    // Create cancellation token for this request
    let cancellation_token = CancellationToken::new();
    let cancel_token_clone = cancellation_token.clone();

    loop {
        attempt += 1;

        // Execute task with cancellation support
        let execution_result = tokio::select! {
            result = agent.execute_task_with_timing_cancellable(
                input, None, false, show_prompt, show_code, true, cancellation_token.clone(), None
            ) => {
                result
            }
            _ = tokio::signal::ctrl_c() => {
                cancel_token_clone.cancel();
                output.print("\n⚠️  Operation cancelled by user (Ctrl+C)");
                return;
            }
        };

        match execution_result {
            Ok(_) => {
                if attempt > 1 {
                    output.print(&format!("✅ Request succeeded after {} attempts", attempt));
                }
                // Response was already displayed during streaming - don't print again
                return;
            }
            Err(e) => {
                if e.to_string().contains("cancelled") {
                    output.print("⚠️  Operation cancelled by user");
                    return;
                }

                // Check if this is a recoverable error that we should retry
                let error_type = classify_error(&e);

                if let ErrorType::Recoverable(recoverable_error) = error_type {
                    if attempt < MAX_RETRIES {
                        // Use shared retry delay calculation (non-autonomous mode)
                        let delay = calculate_retry_delay(attempt, false);
                        let delay_ms = delay.as_millis();

                        output.print(&format!(
                            "⚠️  {} detected (attempt {}/{}). Retrying in {:.1}s...",
                            recoverable_error_name(&recoverable_error),
                            attempt,
                            MAX_RETRIES,
                            delay_ms as f64 / 1000.0
                        ));

                        // Wait before retrying
                        tokio::time::sleep(delay).await;
                        continue;
                    }
                }

                // For non-recoverable errors or after max retries
                handle_execution_error(&e, input, output, attempt);
                return;
            }
        }
    }
}

/// Handle execution errors with detailed logging and user-friendly output.
pub fn handle_execution_error(e: &anyhow::Error, input: &str, output: &SimpleOutput, attempt: u32) {
    // Enhanced error logging with detailed information
    error!("=== TASK EXECUTION ERROR ===");
    error!("Error: {}", e);
    if attempt > 1 {
        error!("Failed after {} attempts", attempt);
    }

    // Log error chain
    let mut source = e.source();
    let mut depth = 1;
    while let Some(err) = source {
        error!("  Caused by [{}]: {}", depth, err);
        source = err.source();
        depth += 1;
    }

    // Log additional context
    error!("Task input: {}", input);
    error!("Error type: {}", std::any::type_name_of_val(&e));

    // Display user-friendly error message
    output.print(&format!("❌ Error: {}", e));

    // If it's a stream error, provide helpful guidance
    if e.to_string().contains("No response received") || e.to_string().contains("timed out") {
        output.print("💡 This may be a temporary issue. Please try again or check the logs for more details.");
        output.print("   Log files are saved in the '.g3/sessions/' directory.");
    }
}