// Copyright (C) 2019-2021 Aleo Systems Inc.
// This file is part of the Leo library.

// The Leo library 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.

// The Leo library 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 the Leo library. If not, see <https://www.gnu.org/licenses/>.

use crate::{
    errors::PackageError,
    imports::ImportsDirectory,
    inputs::{InputFile, InputsDirectory, StateFile},
    root::{Gitignore, Manifest, README},
    source::{MainFile, SourceDirectory},
};

use serde::Deserialize;
use std::path::Path;

#[derive(Deserialize)]
pub struct Package {
    pub name: String,
    pub version: String,
    pub description: Option<String>,
    pub license: Option<String>,
}

impl Package {
    pub fn new(package_name: &str) -> Result<Self, PackageError> {
        // Check that the package name is valid.
        if !Self::is_package_name_valid(package_name) {
            return Err(PackageError::InvalidPackageName(package_name.to_string()));
        }

        Ok(Self {
            name: package_name.to_owned(),
            version: "0.1.0".to_owned(),
            description: None,
            license: None,
        })
    }

    /// Returns `true` if the package name is valid.
    ///
    /// Package names must be lowercase and composed solely
    /// of ASCII alphanumeric characters, and may be word-separated
    /// by a single dash '-'.
    pub fn is_package_name_valid(package_name: &str) -> bool {
        // Check that the package name is nonempty.
        if package_name.is_empty() {
            tracing::error!("Project names must be nonempty");
            return false;
        }

        let mut previous = package_name.chars().next().unwrap();

        // Check that the first character is not a dash.
        if previous == '-' {
            tracing::error!("Project names cannot begin with a dash");
            return false;
        }

        // Check that the first character is not a number.
        if previous.is_numeric() {
            tracing::error!("Project names cannot begin with a number");
            return false;
        }

        // Iterate and check that the package name is valid.
        for current in package_name.chars() {
            // Check that the package name is lowercase.
            if current.is_ascii_uppercase() && current != '-' {
                tracing::error!("Project names must be all lowercase");
                return false;
            }

            // Check that the package name is only ASCII alphanumeric or a dash.
            if !current.is_ascii_alphanumeric() && current != '-' {
                tracing::error!("Project names must be ASCII alphanumeric, and may be word-separated with a dash");
                return false;
            }

            // If the previous character was a dash, check that the current character is not a dash.
            if previous == '-' && current == '-' {
                tracing::error!("Project names may only be word-separated by one dash");
                return false;
            }

            previous = current;
        }

        // Check that the last character is not a dash.
        if previous == '-' {
            tracing::error!("Project names cannot end with a dash");
            return false;
        }

        true
    }

    /// Returns `true` if a package is can be initialized at a given path.
    pub fn can_initialize(package_name: &str, path: &Path) -> bool {
        // Check that the package name is valid.
        if !Self::is_package_name_valid(package_name) {
            return false;
        }

        let mut result = true;
        let mut existing_files = vec![];

        // Check if the manifest file already exists.
        if Manifest::exists_at(path) {
            existing_files.push(Manifest::filename());
            result = false;
        }

        // Check if the input file already exists.
        let input_file = InputFile::new(package_name);
        if input_file.exists_at(path) {
            existing_files.push(input_file.filename());
            result = false;
        }

        // Check if the state file already exists.
        let state_file = StateFile::new(package_name);
        if state_file.exists_at(path) {
            existing_files.push(state_file.filename());
            result = false;
        }

        // Check if the main file already exists.
        if MainFile::exists_at(path) {
            existing_files.push(MainFile::filename());
            result = false;
        }

        if !existing_files.is_empty() {
            tracing::error!("File(s) {:?} already exist", existing_files);
        }

        result
    }

    /// Returns `true` if a package is initialized at the given path
    pub fn is_initialized(package_name: &str, path: &Path) -> bool {
        // Check that the package name is valid.
        if !Self::is_package_name_valid(package_name) {
            return false;
        }

        // Check if the manifest file exists.
        if !Manifest::exists_at(path) {
            return false;
        }

        // Check if the input file exists.
        let input_file = InputFile::new(package_name);
        if !input_file.exists_at(path) {
            return false;
        }

        // Check if the state file exists.
        let state_file = StateFile::new(package_name);
        if !state_file.exists_at(path) {
            return false;
        }

        // Check if the main file exists.
        if !MainFile::exists_at(path) {
            return false;
        }

        true
    }

    /// Creates a package at the given path
    pub fn initialize(package_name: &str, path: &Path, author: Option<String>) -> Result<(), PackageError> {
        // First, verify that this directory is not already initialized as a Leo package.
        {
            if !Self::can_initialize(package_name, path) {
                return Err(PackageError::FailedToInitialize(
                    package_name.to_owned(),
                    path.as_os_str().to_owned(),
                ));
            }
        }
        // Next, initialize this directory as a Leo package.
        {
            // Create the manifest file.
            Manifest::new(package_name, author)?.write_to(path)?;

            // Verify that the .gitignore file does not exist.
            if !Gitignore::exists_at(path) {
                // Create the .gitignore file.
                Gitignore::new().write_to(path)?;
            }

            // Verify that the README.md file does not exist.
            if !README::exists_at(path) {
                // Create the README.md file.
                README::new(package_name).write_to(path)?;
            }

            // Create the source directory.
            SourceDirectory::create(path)?;

            // Create the input directory.
            InputsDirectory::create(path)?;

            // Create the input file in the inputs directory.
            InputFile::new(package_name).write_to(path)?;

            // Create the state file in the inputs directory.
            StateFile::new(package_name).write_to(path)?;

            // Create the main file in the source directory.
            MainFile::new(package_name).write_to(path)?;
        }
        // Next, verify that a valid Leo package has been initialized in this directory
        {
            if !Self::is_initialized(package_name, path) {
                return Err(PackageError::FailedToInitialize(
                    package_name.to_owned(),
                    path.as_os_str().to_owned(),
                ));
            }
        }

        Ok(())
    }

    /// Removes the package at the given path
    pub fn remove_imported_package(package_name: &str, path: &Path) -> Result<(), PackageError> {
        Ok(ImportsDirectory::remove_import(path, package_name)?)
    }
}

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

    #[test]
    fn test_is_package_name_valid() {
        assert!(Package::is_package_name_valid("foo"));
        assert!(Package::is_package_name_valid("foo-bar"));
        assert!(Package::is_package_name_valid("foo-bar-baz"));
        assert!(Package::is_package_name_valid("foo1"));
        assert!(Package::is_package_name_valid("foo-1"));

        assert!(!Package::is_package_name_valid(""));
        assert!(!Package::is_package_name_valid("-"));
        assert!(!Package::is_package_name_valid("-foo"));
        assert!(!Package::is_package_name_valid("-foo-"));
        assert!(!Package::is_package_name_valid("foo--bar"));
        assert!(!Package::is_package_name_valid("foo---bar"));
        assert!(!Package::is_package_name_valid("foo--bar--baz"));
        assert!(!Package::is_package_name_valid("foo---bar---baz"));
        assert!(!Package::is_package_name_valid("foo*bar"));
        assert!(!Package::is_package_name_valid("foo,bar"));
        assert!(!Package::is_package_name_valid("foo_bar"));
        assert!(!Package::is_package_name_valid("1-foo"));
    }
}