// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

//! Parity upgrade logic

use dir::{default_data_path, helpers::replace_home, home_dir, DatabaseDirectories};
use journaldb::Algorithm;
use semver::{SemVerError, Version};
use std::{
    collections::*,
    fs::{self, create_dir_all, File},
    io,
    io::{Read, Write},
    path::{Path, PathBuf},
};

#[derive(Debug)]
pub enum Error {
    CannotCreateConfigPath(io::Error),
    CannotWriteVersionFile(io::Error),
    CannotUpdateVersionFile(io::Error),
    SemVer(SemVerError),
}

impl From<SemVerError> for Error {
    fn from(err: SemVerError) -> Self {
        Error::SemVer(err)
    }
}

const CURRENT_VERSION: &'static str = env!("CARGO_PKG_VERSION");

#[derive(Hash, PartialEq, Eq)]
struct UpgradeKey {
    pub old_version: Version,
    pub new_version: Version,
}

type UpgradeList = HashMap<UpgradeKey, fn() -> Result<(), Error>>;

impl UpgradeKey {
    // given the following config exist
    // ver.lock 1.1 (`previous_version`)
    //
    //  current_version 1.4 (`current_version`)
    //
    //
    //upgrades (set of `UpgradeKey`)
    //	1.0 -> 1.1 (u1)
    //	1.1 -> 1.2 (u2)
    //	1.2 -> 1.3 (u3)
    //	1.3 -> 1.4 (u4)
    //	1.4 -> 1.5 (u5)
    //
    // then the following upgrades should be applied:
    // u2, u3, u4
    fn is_applicable(&self, previous_version: &Version, current_version: &Version) -> bool {
        self.old_version >= *previous_version && self.new_version <= *current_version
    }
}

// dummy upgrade (remove when the first one is in)
fn dummy_upgrade() -> Result<(), Error> {
    Ok(())
}

fn push_upgrades(upgrades: &mut UpgradeList) {
    // dummy upgrade (remove when the first one is in)
    upgrades.insert(
        UpgradeKey {
            old_version: Version::new(0, 9, 0),
            new_version: Version::new(1, 0, 0),
        },
        dummy_upgrade,
    );
}

fn upgrade_from_version(previous_version: &Version) -> Result<usize, Error> {
    let mut upgrades = HashMap::new();
    push_upgrades(&mut upgrades);

    let current_version = Version::parse(CURRENT_VERSION)?;

    let mut count = 0;
    for upgrade_key in upgrades.keys() {
        if upgrade_key.is_applicable(previous_version, &current_version) {
            let upgrade_script = upgrades[upgrade_key];
            upgrade_script()?;
            count += 1;
        }
    }
    Ok(count)
}

fn with_locked_version<F>(db_path: &str, script: F) -> Result<usize, Error>
where
    F: Fn(&Version) -> Result<usize, Error>,
{
    let mut path = PathBuf::from(db_path);
    create_dir_all(&path).map_err(Error::CannotCreateConfigPath)?;
    path.push("ver.lock");

    let version = File::open(&path)
        .ok()
        .and_then(|ref mut file| {
            let mut version_string = String::new();
            file.read_to_string(&mut version_string)
                .ok()
                .and_then(|_| Version::parse(&version_string).ok())
        })
        .unwrap_or(Version::new(0, 9, 0));

    let mut lock = File::create(&path).map_err(Error::CannotWriteVersionFile)?;
    let result = script(&version);

    let written_version = Version::parse(CURRENT_VERSION)?;
    lock.write_all(written_version.to_string().as_bytes())
        .map_err(Error::CannotUpdateVersionFile)?;
    result
}

pub fn upgrade(db_path: &str) -> Result<usize, Error> {
    with_locked_version(db_path, |ver| upgrade_from_version(ver))
}

fn file_exists(path: &Path) -> bool {
    match fs::metadata(&path) {
        Err(ref e) if e.kind() == io::ErrorKind::NotFound => false,
        _ => true,
    }
}

#[cfg(any(test, feature = "accounts"))]
pub fn upgrade_key_location(from: &PathBuf, to: &PathBuf) {
    match fs::create_dir_all(&to).and_then(|()| fs::read_dir(from)) {
        Ok(entries) => {
            let files: Vec<_> = entries
                .filter_map(|f| {
                    f.ok().and_then(|f| {
                        if f.file_type().ok().map_or(false, |f| f.is_file()) {
                            f.file_name().to_str().map(|s| s.to_owned())
                        } else {
                            None
                        }
                    })
                })
                .collect();
            let mut num: usize = 0;
            for name in files {
                let mut from = from.clone();
                from.push(&name);
                let mut to = to.clone();
                to.push(&name);
                if !file_exists(&to) {
                    if let Err(e) = fs::rename(&from, &to) {
                        debug!("Error upgrading key {:?}: {:?}", from, e);
                    } else {
                        num += 1;
                    }
                } else {
                    debug!("Skipped upgrading key {:?}", from);
                }
            }
            if num > 0 {
                info!(
                    "Moved {} keys from {} to {}",
                    num,
                    from.to_string_lossy(),
                    to.to_string_lossy()
                );
            }
        }
        Err(e) => {
            debug!("Error moving keys from {:?} to {:?}: {:?}", from, to, e);
        }
    }
}

fn upgrade_dir_location(source: &PathBuf, dest: &PathBuf) {
    if file_exists(&source) {
        if !file_exists(&dest) {
            let mut parent = dest.clone();
            parent.pop();
            if let Err(e) = fs::create_dir_all(&parent).and_then(|()| fs::rename(&source, &dest)) {
                debug!("Skipped path {:?} -> {:?} :{:?}", source, dest, e);
            } else {
                info!(
                    "Moved {} to {}",
                    source.to_string_lossy(),
                    dest.to_string_lossy()
                );
            }
        } else {
            debug!(
                "Skipped upgrading directory {:?}, Destination already exists at {:?}",
                source, dest
            );
        }
    }
}

fn upgrade_user_defaults(dirs: &DatabaseDirectories) {
    let source = dirs.legacy_user_defaults_path();
    let dest = dirs.user_defaults_path();
    if file_exists(&source) {
        if !file_exists(&dest) {
            if let Err(e) = fs::rename(&source, &dest) {
                debug!("Skipped upgrading user defaults {:?}:{:?}", dest, e);
            }
        } else {
            debug!(
                "Skipped upgrading user defaults {:?}, File exists at {:?}",
                source, dest
            );
        }
    }
}

pub fn upgrade_data_paths(base_path: &str, dirs: &DatabaseDirectories, pruning: Algorithm) {
    if home_dir().is_none() {
        return;
    }

    let legacy_root_path = replace_home("", "$HOME/.parity");
    let default_path = default_data_path();
    if legacy_root_path != base_path && base_path == default_path {
        upgrade_dir_location(&PathBuf::from(legacy_root_path), &PathBuf::from(&base_path));
    }
    upgrade_dir_location(&dirs.legacy_version_path(pruning), &dirs.db_path(pruning));
    upgrade_dir_location(&dirs.legacy_snapshot_path(), &dirs.snapshot_path());
    upgrade_dir_location(&dirs.legacy_network_path(), &dirs.network_path());
    upgrade_user_defaults(&dirs);
}