use crate::tools;

use failure::*;
use regex::Regex;

use chrono::{DateTime, TimeZone, Local};

use std::path::{PathBuf, Path};
use lazy_static::lazy_static;

macro_rules! BACKUP_ID_RE { () => (r"[A-Za-z0-9][A-Za-z0-9_-]+") }
macro_rules! BACKUP_TYPE_RE { () => (r"(?:host|vm|ct)") }
macro_rules! BACKUP_TIME_RE { () => (r"[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}\+[0-9]{2}:[0-9]{2}") }

lazy_static!{
    static ref BACKUP_FILE_REGEX: Regex = Regex::new(
        r"^.*\.([fd]idx)$").unwrap();

    static ref BACKUP_TYPE_REGEX: Regex = Regex::new(
        concat!(r"^(", BACKUP_TYPE_RE!(), r")$")).unwrap();

    static ref BACKUP_ID_REGEX: Regex = Regex::new(
        concat!(r"^", BACKUP_ID_RE!(), r"$")).unwrap();

    static ref BACKUP_DATE_REGEX: Regex = Regex::new(
        concat!(r"^", BACKUP_TIME_RE!() ,r"$")).unwrap();

    static ref GROUP_PATH_REGEX: Regex = Regex::new(
        concat!(r"(", BACKUP_TYPE_RE!(), ")/(", BACKUP_ID_RE!(), r")$")).unwrap();

    static ref SNAPSHOT_PATH_REGEX: Regex = Regex::new(
        concat!(r"(", BACKUP_TYPE_RE!(), ")/(", BACKUP_ID_RE!(), ")/(", BACKUP_TIME_RE!(), r")$")).unwrap();

}

/// BackupGroup is a directory containing a list of BackupDir
#[derive(Debug)]
pub struct BackupGroup {
    /// Type of backup
    backup_type: String,
    /// Unique (for this type) ID
    backup_id: String,
}

impl BackupGroup {

    pub fn new<T: Into<String>>(backup_type: T, backup_id: T) -> Self {
        Self { backup_type: backup_type.into(), backup_id: backup_id.into() }
    }

    pub fn backup_type(&self) -> &str {
        &self.backup_type
    }

    pub fn backup_id(&self) -> &str {
        &self.backup_id
    }

    pub fn parse(path: &str) -> Result<Self, Error> {

        let cap = GROUP_PATH_REGEX.captures(path)
            .ok_or_else(|| format_err!("unable to parse backup group path '{}'", path))?;

        Ok(Self {
            backup_type: cap.get(1).unwrap().as_str().to_owned(),
            backup_id: cap.get(2).unwrap().as_str().to_owned(),
        })
    }

    pub fn group_path(&self) ->  PathBuf  {

        let mut relative_path = PathBuf::new();

        relative_path.push(&self.backup_type);

        relative_path.push(&self.backup_id);

        relative_path
    }
}

/// Uniquely identify a Backup (relative to data store)
///
/// We also call this a backup snaphost.
#[derive(Debug)]
pub struct BackupDir {
    /// Backup group
    group: BackupGroup,
    /// Backup timestamp
    backup_time: DateTime<Local>,
}

impl BackupDir {

    pub fn new(group: BackupGroup, timestamp: i64) -> Self {
        // Note: makes sure that nanoseconds is 0
        Self { group, backup_time: Local.timestamp(timestamp, 0) }
    }

    pub fn group(&self) -> &BackupGroup {
        &self.group
    }

    pub fn backup_time(&self) -> DateTime<Local> {
        self.backup_time
    }

    pub fn parse(path: &str) -> Result<Self, Error> {

        let cap = SNAPSHOT_PATH_REGEX.captures(path)
            .ok_or_else(|| format_err!("unable to parse backup snapshot path '{}'", path))?;

        let group = BackupGroup::new(cap.get(1).unwrap().as_str(), cap.get(2).unwrap().as_str());
        let backup_time = cap.get(3).unwrap().as_str().parse::<DateTime<Local>>()?;
        Ok(BackupDir::new(group, backup_time.timestamp()))
    }

    pub fn relative_path(&self) ->  PathBuf  {

        let mut relative_path = self.group.group_path();

        relative_path.push(self.backup_time.to_rfc3339());

        relative_path
    }
}

/// Detailed Backup Information, lists files inside a BackupDir
#[derive(Debug)]
pub struct BackupInfo {
    /// the backup directory
    pub backup_dir: BackupDir,
    /// List of data files
    pub files: Vec<String>,
}

impl BackupInfo {

    pub fn sort_list(list: &mut Vec<BackupInfo>, ascendending: bool) {
        if ascendending { // oldest first
            list.sort_unstable_by(|a, b| a.backup_dir.backup_time.cmp(&b.backup_dir.backup_time));
        } else { // newest first
            list.sort_unstable_by(|a, b| b.backup_dir.backup_time.cmp(&a.backup_dir.backup_time));
        }
    }

    pub fn list_backups(path: &Path) -> Result<Vec<BackupInfo>, Error> {
        let mut list = vec![];

        tools::scandir(libc::AT_FDCWD, path, &BACKUP_TYPE_REGEX, |l0_fd, backup_type, file_type| {
            if file_type != nix::dir::Type::Directory { return Ok(()); }
            tools::scandir(l0_fd, backup_type, &BACKUP_ID_REGEX, |l1_fd, backup_id, file_type| {
                if file_type != nix::dir::Type::Directory { return Ok(()); }
                tools::scandir(l1_fd, backup_id, &BACKUP_DATE_REGEX, |l2_fd, backup_time, file_type| {
                    if file_type != nix::dir::Type::Directory { return Ok(()); }

                    let dt = backup_time.parse::<DateTime<Local>>()?;

                    let mut files = vec![];

                    tools::scandir(l2_fd, backup_time, &BACKUP_FILE_REGEX, |_, filename, file_type| {
                        if file_type != nix::dir::Type::File { return Ok(()); }
                        files.push(filename.to_owned());
                        Ok(())
                    })?;

                    list.push(BackupInfo {
                        backup_dir: BackupDir::new(BackupGroup::new(backup_type, backup_id), dt.timestamp()),
                        files,
                    });

                    Ok(())
                })
            })
        })?;
        Ok(list)
    }
}