use pest::Parser;
use pest_derive::Parser;
use std::collections::HashMap;

#[derive(Parser)]
#[grammar = "filter.pest"]
pub struct FilterParser;

#[derive(Debug)]
pub struct Filter {
    pub name: String,
    pub options: HashMap<String, serde_json::Value>,
}

pub fn parse_filter_string(input: &str) -> Result<Vec<Filter>, Box<dyn std::error::Error>> {
    let mut filters = Vec::new();
    let pairs = FilterParser::parse(Rule::filters, input)?;
    
    for pair in pairs {
        if pair.as_rule() == Rule::filter {
            let mut name = String::new();
            let mut options = HashMap::new();
            
            for inner_pair in pair.into_inner() {
                match inner_pair.as_rule() {
                    Rule::filter_name => {
                        name = inner_pair.as_str().to_string();
                    }
                    Rule::options => {
                        for option_pair in inner_pair.into_inner() {
                            if option_pair.as_rule() == Rule::option {
                                let mut option_name = None;
                                let mut option_value = None;
                                
                                for option_inner in option_pair.into_inner() {
                                    match option_inner.as_rule() {
                                        Rule::option_name => {
                                            option_name = Some(option_inner.as_str().to_string());
                                        }
                                        Rule::option_value => {
                                            option_value = Some(parse_option_value(option_inner.as_str())?);
                                        }
                                        _ => {}
                                    }
                                }
                                
                                if let Some(value) = option_value {
                                    // If no name is provided, use the filter name as the key
                                    let key = option_name.unwrap_or_else(|| name.clone());
                                    options.insert(key, value);
                                }
                            }
                        }
                    }
                    _ => {}
                }
            }
            
            filters.push(Filter { name, options });
        }
    }
    
    Ok(filters)
}

fn parse_option_value(input: &str) -> Result<serde_json::Value, Box<dyn std::error::Error>> {
    // Try to parse as number
    if let Ok(num) = input.parse::<i64>() {
        return Ok(serde_json::Value::Number(num.into()));
    }
    if let Ok(num) = input.parse::<f64>() {
        if let Some(number) = serde_json::Number::from_f64(num) {
            return Ok(serde_json::Value::Number(number));
        }
    }
    
    // Try to parse as boolean
    if let Ok(boolean) = input.parse::<bool>() {
        return Ok(serde_json::Value::Bool(boolean));
    }
    
    // Treat as string (remove quotes if present)
    let value = if input.starts_with('"') && input.ends_with('"') {
        input[1..input.len()-1].to_string()
    } else if input.starts_with('\'') && input.ends_with('\'') {
        input[1..input.len()-1].to_string()
    } else {
        input.to_string()
    };
    
    Ok(serde_json::Value::String(value))
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_parse_simple_filter() {
        let result = parse_filter_string("grep").unwrap();
        assert_eq!(result.len(), 1);
        assert_eq!(result[0].name, "grep");
        assert!(result[0].options.is_empty());
    }
    
    #[test]
    fn test_parse_filter_with_options() {
        let result = parse_filter_string("head_lines(10)").unwrap();
        assert_eq!(result.len(), 1);
        assert_eq!(result[0].name, "head_lines");
        assert_eq!(result[0].options["head_lines"], 10);
    }
    
    #[test]
    fn test_parse_filter_with_named_options() {
        let result = parse_filter_string("grep(pattern=\"error\")").unwrap();
        assert_eq!(result.len(), 1);
        assert_eq!(result[0].name, "grep");
        assert_eq!(result[0].options["pattern"], "error");
    }
    
    #[test]
    fn test_parse_multiple_filters() {
        let result = parse_filter_string("head_lines(10), grep(pattern=\"error\")").unwrap();
        assert_eq!(result.len(), 2);
        assert_eq!(result[0].name, "head_lines");
        assert_eq!(result[0].options["head_lines"], 10);
        assert_eq!(result[1].name, "grep");
        assert_eq!(result[1].options["pattern"], "error");
    }
}