use common::request::Request;

use argon2::{Argon2, PasswordHash, PasswordVerifier};

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

#[derive(Clone)]
pub struct PasswordDirectory {
    dir_path: PathBuf,
}

impl PasswordDirectory {
    pub fn new(path: &str) -> PasswordDirectory {
        PasswordDirectory {
            dir_path: PathBuf::from(path),
        }
    }

    /// Read all the non-blank and non-comment lines in a password file
    ///
    fn read_password_lines(&self, request: &Request) -> Vec<String> {
        let mut file_name = self.dir_path.clone();
        file_name.push(&request.userid);

        let mut result = Vec::new();

        if let Ok(file) = File::open(file_name) {
            for line in BufReader::new(file).lines().map_while(Result::ok) {
                if !line.starts_with('#') {
                    let trimmed = line.trim();
                    if !trimmed.is_empty() {
                        result.push(line);
                    }
                }
            }
        }

        result
    }

    /// The password sent by the user is like "[{id}]{plain-text-password}"
    /// so try to find a line with a matching "[{id}]" and see if the hash stored
    /// there corresponds to the {plain-text-password}
    ///
    fn check_hashed_password(&self, lines: &Vec<String>, password: &str) -> bool {
        let (key, split_password) = password.strip_prefix('[').unwrap().split_once(']').unwrap();
        info!("    looking for password-key: [{}]", key);

        let mut result = false;

        for line in lines {
            if line.starts_with('[') && line.contains(']') {
                let (line_key, line_hash) =
                    line.strip_prefix('[').unwrap().split_once(']').unwrap();

                if line_key == key
                    && let Ok(parsed_hash) = PasswordHash::new(line_hash)
                    && Argon2::default()
                        .verify_password(split_password.as_bytes(), &parsed_hash)
                        .is_ok()
                {
                    result = true;
                }
            }
        }

        result
    }

    fn check_plain_password(&self, lines: &Vec<String>, password: &str) -> bool {
        info!("    looking for plain password");

        let mut result = false;

        for line in lines {
            // Ignore lines that are the hashed passwords with ids, but still take
            // lines that contain ']' if they don't also start with '['
            //
            if !(line.starts_with('[') && line.contains(']')) && line == password {
                result = true;
            }
        }

        result
    }

    pub fn check_auth(&self, request: &Request) -> bool {
        // Don't allow empty userids or test_passwords
        //
        if request.userid.is_empty() || request.userid.contains('/') || request.password.is_empty()
        {
            return false;
        }

        let lines = self.read_password_lines(request);

        if request.password.starts_with('[') && request.password.contains("]") {
            self.check_hashed_password(&lines, &request.password)
        } else {
            self.check_plain_password(&lines, &request.password)
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::repository::PasswordDirectory;
    use argon2::{Argon2, PasswordHash, PasswordVerifier};
    use common::request::Request;

    const TEST_PATH: &str = "../test_passwords";

    #[test]

    /// Make sure hash checking is working as expected
    ///
    fn it_checks_argon2() {
        let password = b"hunter2";

        // Generated with
        //    echo -n "hunter2" | argon2 "$(openssl rand -base64 16)" -id
        let password_hash = "$argon2id$v=19$m=4096,t=3,p=1$VTMrc2wyaW93L01ibVFPOGNQcHcxQT09$UxX86sGpknkc45CnXq+4CZ0coiTYDvSWIN7JgbeAZUs";

        let parsed_hash = PasswordHash::new(password_hash).unwrap();
        assert!(
            Argon2::default()
                .verify_password(password, &parsed_hash)
                .is_ok()
        );
    }

    #[test]
    fn it_checks_good_password() {
        let repository = PasswordDirectory::new(TEST_PATH);

        let request = Request::new("bp", "some-rad-password", "ignore-this", "also-ignore-this");

        assert!(repository.check_auth(&request));
    }

    #[test]
    fn it_checks_good_hashed_password() {
        let repository = PasswordDirectory::new(TEST_PATH);

        let request = Request::new("bp", "[id-1]hunter2", "ignore-this", "also-ignore-this");

        assert!(repository.check_auth(&request));
    }

    /// The key [id-1] is present in the test file, but the hash shouldn't match
    ///
    #[test]
    fn it_checks_bad_hashed_password() {
        let repository = PasswordDirectory::new(TEST_PATH);

        let request = Request::new("bp", "[id-1]hunter-bad", "ignore-this", "also-ignore-this");

        assert!(!repository.check_auth(&request));
    }

    /// The key [id-2] is not present in the test file
    ///
    #[test]
    fn it_checks_missing_hashed_password() {
        let repository = PasswordDirectory::new(TEST_PATH);

        let request = Request::new("bp", "[id-2]hunter", "ignore-this", "also-ignore-this");

        assert!(!repository.check_auth(&request));
    }

    #[test]
    fn it_fails_bad_password() {
        let repository = PasswordDirectory::new(TEST_PATH);

        let request = Request::new("bp", "not-correct", "ignore-this", "also-ignore-this");

        assert!(!repository.check_auth(&request));
    }

    #[test]
    fn it_fails_bad_userid() {
        let repository = PasswordDirectory::new(TEST_PATH);

        let request = Request::new(
            "bp-xxx",
            "some-rad-password",
            "ignore-this",
            "also-ignore-this",
        );

        assert!(!repository.check_auth(&request));
    }

    #[test]
    fn it_ignores_comments() {
        let repository = PasswordDirectory::new(TEST_PATH);

        let request = Request::new("bp-xxx", "commented-out", "ignore-this", "also-ignore-this");

        assert!(!repository.check_auth(&request));
    }
}