use std::error::Error;
use std::fmt;

pub struct Config {
    pub query: String,
    pub filename: String,
    pub sensitive: bool,
}

impl Config {
    pub fn new(args: &[String]) -> Result<Config, &'static str> {
        if args.len() < 2 {
            return Err("args len less then 2");
        }
        let query = args[0].clone();
        let filename = args[1].clone();
        let sensitive = std::env::var("CASE_SENSITIVE").is_ok();
        Ok(Config {
            query,
            filename,
            sensitive,
        })
    }
}

pub struct GrepRet {
    line: i32,
    context: String,
}
impl GrepRet {
    fn new(line: i32, context: &str) -> GrepRet {
        GrepRet {
            line,
            context: context.to_string(),
        }
    }
}
impl fmt::Display for GrepRet {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "line:{}: {}", self.line, self.context)
    }
}
pub fn run(config: &Config) -> Result<Vec<GrepRet>, Box<dyn Error>> {
    let context = std::fs::read_to_string(&config.filename)?;
    if config.sensitive {
        Ok(search_sensitive(&config.query, &context))
    } else {
        Ok(search_insensitive(&config.query, &context))
    }
}

fn search_sensitive(query: &str, context: &String) -> Vec<GrepRet> {
    let mut idx = 0;
    let mut result = Vec::new();
    for line in context.lines() {
        idx += 1;
        if line.contains(query) {
            result.push(GrepRet::new(idx, line));
        }
    }
    result
}

fn search_insensitive(query: &str, context: &String) -> Vec<GrepRet> {
    let mut idx = 0;
    let mut result = Vec::new();
    for line in context.lines() {
        idx += 1;
        let lower = line.to_lowercase();
        if lower.contains(&query.to_lowercase()) {
            result.push(GrepRet::new(idx, line));
        }
    }
    result
}

#[cfg(test)]
pub mod test {
    use super::*;
    #[test]
    fn grep_new1() {
        let line = 10;
        let context = "zzz";
        let grep_ret = GrepRet::new(line, context);
        assert_eq!(line, grep_ret.line);
        assert_eq!(context, grep_ret.context);
    }
    #[test]
    fn grep_new2() {
        let line = 10;
        let context = "zzz";
        let grep_ret = GrepRet::new(line, context);
        assert_ne!(!line, grep_ret.line);
        assert_eq!(context, grep_ret.context);
    }

    #[test]
    #[ignore] // cargo test -- --ignored
    fn grep_new3() {
        let line = 10;
        let context = "zzz";
        let grep_ret = GrepRet::new(line, context);
        assert_ne!(!line, grep_ret.line);
        assert_eq!(context, grep_ret.context);
    }
}