use std::{
    fs::File,
    io::{BufRead, BufReader},
    path::{Path, PathBuf},
};

use anyhow::Context;
use regex::Regex;

use crate::matches::{Match, Matches};

pub fn process_files(
    file_paths: &Vec<PathBuf>,
    pattern: &str,
) -> anyhow::Result<Matches, anyhow::Error> {
    let mut matches = Matches { items: vec![], pattern: String::from(pattern) };

    for file_path in file_paths {
        let lines_iter = read_lines(file_path)?;
        let mut _matches = match_pattern(lines_iter, pattern, file_path)?;
        matches.append(&mut _matches);
    }

    // let lines_iter = read_lines(file_path)?;
    // let matches = match_pattern(lines_iter, pattern, file_path)?;

    Ok(matches)
}

pub fn read_lines(
    file_path: &Path,
) -> anyhow::Result<impl Iterator<Item = std::io::Result<String>>, anyhow::Error> {
    match file_path.try_exists() {
        Ok(true) => {}
        Ok(false) => return Err(anyhow::anyhow!("File path needs to exist")),
        Err(e) => eprintln!("Error checking path: {e}"),
    }

    let path_string = file_path.to_string_lossy().to_string();

    let file =
        File::open(file_path).with_context(|| format!("failed to open file: {path_string}"))?;
    let reader = BufReader::new(file);

    Ok(reader.lines())
}

fn get_file_name_from_path(file_path: &Path) -> String {
    match file_path.file_name() {
        Some(name) => name.to_string_lossy().to_string(),
        None => String::from("unknown"),
    }
}

pub fn match_pattern(
    iter: impl Iterator<Item = std::io::Result<String>>,
    pattern: &str,
    file_path: &Path,
) -> anyhow::Result<Matches, anyhow::Error> {
    let reg = Regex::new(pattern).with_context(|| format!("invalid regex: {:?}", pattern))?;
    let mut matches = Vec::new();

    for (idx, line) in iter.enumerate() {
        let line = line?;

        if reg.is_match(&line) {
            let m = Match {
                line_number: idx + 1,
                text: line,
                file_name: get_file_name_from_path(file_path),
            };

            matches.push(m);
        }
    }

    Ok(Matches { items: matches, pattern: String::from(pattern) })
}

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

    #[test]
    fn test_get_file_name_from_path() {
        let path = Path::new("/path/to/file.txt");
        let file_name = get_file_name_from_path(path);
        assert_eq!(file_name, "file.txt");

        let path = Path::new("file.txt");
        let file_name = get_file_name_from_path(path);
        assert_eq!(file_name, "file.txt");
    }

    #[test]
    fn matches_lines_and_tracks_line_numbers() {
        let input: Vec<std::io::Result<String>> =
            vec![Ok("hola".into()), Ok("no".into()), Ok("hola again".into())];

        let result =
            match_pattern(input.into_iter(), r"^hola", Path::new("/tmp/test.txt")).unwrap();

        assert_eq!(result.items.len(), 2);

        assert_eq!(result.items[0].text, "hola");
        assert_eq!(result.items[0].line_number, 1);
        assert_eq!(result.items[0].file_name, "test.txt");

        assert_eq!(result.items[1].text, "hola again");
        assert_eq!(result.items[1].line_number, 3);
    }
}