use actix_web::{Error, HttpResponse};
use chrono::{DateTime, Utc};
use std::error::Error as StdError;
use tera::{self, Context, Function, Tera, Value};

// Export modules
pub mod redis_service;

// Re-export for easier imports
// pub use redis_service::RedisCalendarService; // Currently unused

/// Error type for template rendering
#[derive(Debug)]
#[allow(dead_code)]
pub struct TemplateError {
    pub message: String,
    pub details: String,
    pub location: String,
}

impl std::fmt::Display for TemplateError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "Template error in {}: {}", self.location, self.message)
    }
}

impl std::error::Error for TemplateError {}

/// Registers custom Tera functions and filters
pub fn register_tera_functions(tera: &mut tera::Tera) {
    tera.register_function("now", NowFunction);
    tera.register_function("format_date", FormatDateFunction);
    tera.register_function("local_time", LocalTimeFunction);

    // Register custom filters
    tera.register_filter("format_hour", format_hour_filter);
    tera.register_filter("extract_hour", extract_hour_filter);
    tera.register_filter("format_time", format_time_filter);
}

/// Tera function to get the current date/time
#[derive(Clone)]
pub struct NowFunction;

impl Function for NowFunction {
    fn call(&self, args: &std::collections::HashMap<String, Value>) -> tera::Result<Value> {
        let format = match args.get("format") {
            Some(val) => match val.as_str() {
                Some(s) => s,
                None => "%Y-%m-%d %H:%M:%S",
            },
            None => "%Y-%m-%d %H:%M:%S",
        };

        let now = Utc::now();

        // Special case for just getting the year
        if args.get("year").and_then(|v| v.as_bool()).unwrap_or(false) {
            return Ok(Value::String(now.format("%Y").to_string()));
        }

        Ok(Value::String(now.format(format).to_string()))
    }
}

/// Tera function to format a date
#[derive(Clone)]
pub struct FormatDateFunction;

impl Function for FormatDateFunction {
    fn call(&self, args: &std::collections::HashMap<String, Value>) -> tera::Result<Value> {
        let timestamp = match args.get("timestamp") {
            Some(val) => match val.as_i64() {
                Some(ts) => ts,
                None => {
                    return Err(tera::Error::msg(
                        "The 'timestamp' argument must be a valid timestamp",
                    ));
                }
            },
            None => return Err(tera::Error::msg("The 'timestamp' argument is required")),
        };

        let format = match args.get("format") {
            Some(val) => match val.as_str() {
                Some(s) => s,
                None => "%Y-%m-%d %H:%M:%S",
            },
            None => "%Y-%m-%d %H:%M:%S",
        };

        // Convert timestamp to DateTime using the non-deprecated method
        let datetime = match DateTime::from_timestamp(timestamp, 0) {
            Some(dt) => dt,
            None => return Err(tera::Error::msg("Failed to convert timestamp to datetime")),
        };

        Ok(Value::String(datetime.format(format).to_string()))
    }
}

/// Tera function to convert UTC datetime to local time
#[derive(Clone)]
pub struct LocalTimeFunction;

impl Function for LocalTimeFunction {
    fn call(&self, args: &std::collections::HashMap<String, Value>) -> tera::Result<Value> {
        let datetime_value = match args.get("datetime") {
            Some(val) => val,
            None => return Err(tera::Error::msg("The 'datetime' argument is required")),
        };

        let format = match args.get("format") {
            Some(val) => match val.as_str() {
                Some(s) => s,
                None => "%Y-%m-%d %H:%M",
            },
            None => "%Y-%m-%d %H:%M",
        };

        // The datetime comes from Rust as a serialized DateTime<Utc>
        // We need to handle it properly
        let utc_datetime = if let Some(dt_str) = datetime_value.as_str() {
            // Try to parse as RFC3339 first
            match DateTime::parse_from_rfc3339(dt_str) {
                Ok(dt) => dt.with_timezone(&Utc),
                Err(_) => {
                    // Try to parse as our standard format
                    match DateTime::parse_from_str(dt_str, "%Y-%m-%d %H:%M:%S%.f UTC") {
                        Ok(dt) => dt.with_timezone(&Utc),
                        Err(_) => return Err(tera::Error::msg("Invalid datetime string format")),
                    }
                }
            }
        } else {
            return Err(tera::Error::msg("Datetime must be a string"));
        };

        // Convert UTC to local time (EEST = UTC+3)
        // In a real application, you'd want to get the user's timezone from their profile
        let local_offset = chrono::FixedOffset::east_opt(3 * 3600).unwrap(); // +3 hours for EEST
        let local_datetime = utc_datetime.with_timezone(&local_offset);

        Ok(Value::String(local_datetime.format(format).to_string()))
    }
}

/// Tera filter to format hour with zero padding
pub fn format_hour_filter(
    value: &Value,
    _args: &std::collections::HashMap<String, Value>,
) -> tera::Result<Value> {
    match value.as_i64() {
        Some(hour) => Ok(Value::String(format!("{:02}", hour))),
        None => Err(tera::Error::msg("Value must be a number")),
    }
}

/// Tera filter to extract hour from datetime string
pub fn extract_hour_filter(
    value: &Value,
    _args: &std::collections::HashMap<String, Value>,
) -> tera::Result<Value> {
    match value.as_str() {
        Some(datetime_str) => {
            // Try to parse as RFC3339 first
            if let Ok(dt) = DateTime::parse_from_rfc3339(datetime_str) {
                Ok(Value::String(dt.format("%H").to_string()))
            } else {
                // Try to parse as our standard format
                match DateTime::parse_from_str(datetime_str, "%Y-%m-%d %H:%M:%S%.f UTC") {
                    Ok(dt) => Ok(Value::String(dt.format("%H").to_string())),
                    Err(_) => Err(tera::Error::msg("Invalid datetime string format")),
                }
            }
        }
        None => Err(tera::Error::msg("Value must be a string")),
    }
}

/// Tera filter to format time from datetime string
pub fn format_time_filter(
    value: &Value,
    args: &std::collections::HashMap<String, Value>,
) -> tera::Result<Value> {
    let format = match args.get("format") {
        Some(val) => match val.as_str() {
            Some(s) => s,
            None => "%H:%M",
        },
        None => "%H:%M",
    };

    match value.as_str() {
        Some(datetime_str) => {
            // Try to parse as RFC3339 first
            if let Ok(dt) = DateTime::parse_from_rfc3339(datetime_str) {
                Ok(Value::String(dt.format(format).to_string()))
            } else {
                // Try to parse as our standard format
                match DateTime::parse_from_str(datetime_str, "%Y-%m-%d %H:%M:%S%.f UTC") {
                    Ok(dt) => Ok(Value::String(dt.format(format).to_string())),
                    Err(_) => Err(tera::Error::msg("Invalid datetime string format")),
                }
            }
        }
        None => Err(tera::Error::msg("Value must be a string")),
    }
}

/// Formats a date for display
#[allow(dead_code)]
pub fn format_date(date: &DateTime<Utc>, format: &str) -> String {
    date.format(format).to_string()
}

/// Truncates a string to a maximum length and adds an ellipsis if truncated
#[allow(dead_code)]
pub fn truncate_string(s: &str, max_length: usize) -> String {
    if s.len() <= max_length {
        s.to_string()
    } else {
        format!("{}...", &s[0..max_length])
    }
}

/// Renders a template with error handling
///
/// This function attempts to render a template and handles any errors by rendering
/// the error template with detailed error information.
pub fn render_template(
    tmpl: &Tera,
    template_name: &str,
    ctx: &Context,
) -> Result<HttpResponse, Error> {
    println!("DEBUG: Attempting to render template: {}", template_name);

    // Print all context keys for debugging
    let mut keys = Vec::new();
    for (key, _) in ctx.clone().into_json().as_object().unwrap().iter() {
        keys.push(key.clone());
    }
    println!("DEBUG: Context keys: {:?}", keys);

    match tmpl.render(template_name, ctx) {
        Ok(content) => {
            println!("DEBUG: Successfully rendered template: {}", template_name);
            Ok(HttpResponse::Ok().content_type("text/html").body(content))
        }
        Err(e) => {
            // Log the error with more details
            println!(
                "DEBUG: Template rendering error for {}: {}",
                template_name, e
            );
            println!("DEBUG: Error details: {:?}", e);

            // Print the error cause chain for better debugging
            let mut current_error: Option<&dyn StdError> = Some(&e);
            let mut error_chain = Vec::new();

            while let Some(error) = current_error {
                error_chain.push(format!("{}", error));
                current_error = error.source();
            }

            println!("DEBUG: Error chain: {:?}", error_chain);

            // Log the error
            log::error!("Template rendering error: {}", e);

            // Create a simple error response with more detailed information
            let error_html = format!(
                r#"<!DOCTYPE html>
                <html>
                <head>
                    <title>Template Error</title>
                    <style>
                        body {{ font-family: Arial, sans-serif; margin: 40px; line-height: 1.6; }}
                        .error-container {{ border: 1px solid #f5c6cb; background-color: #f8d7da; padding: 20px; border-radius: 5px; }}
                        .error-title {{ color: #721c24; }}
                        .error-details {{ background-color: #f8f9fa; padding: 15px; border-radius: 5px; margin-top: 20px; }}
                        pre {{ background-color: #f1f1f1; padding: 10px; overflow: auto; }}
                    </style>
                </head>
                <body>
                    <div class="error-container">
                        <h1 class="error-title">Template Rendering Error</h1>
                        <p>There was an error rendering the template: <strong>{}</strong></p>
                        <div class="error-details">
                            <h3>Error Details:</h3>
                            <pre>{}</pre>
                            <h3>Error Chain:</h3>
                            <pre>{}</pre>
                        </div>
                    </div>
                </body>
                </html>"#,
                template_name,
                e,
                error_chain.join("\n")
            );

            println!("DEBUG: Returning simple error page");

            Ok(HttpResponse::InternalServerError()
                .content_type("text/html")
                .body(error_html))
        }
    }
}

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

    #[test]
    fn test_truncate_string() {
        assert_eq!(truncate_string("Hello", 10), "Hello");
        assert_eq!(truncate_string("Hello, world!", 5), "Hello...");
        assert_eq!(truncate_string("", 5), "");
    }
}