//! # Init operations
//!
//! The init module contains functionality relating to the init command,
//! independent of the CLI.

use std::{fs::create_dir_all, path::PathBuf};

use git2::Repository;

use crate::{config::Config, errors::DiaryError};

/// The options available to the init command.
pub struct InitOptions {
    /// The path to initialise the diary folder.
    pub path: PathBuf,
    /// The prefix to use for the diary entries.
    pub prefix: Option<String>,
    /// Whether or not to init a git repo.
    pub git_repo: bool,
}

enum InitStatus {
    UseConfig(PathBuf),
    UseOpt(PathBuf),
}

/// Establishes where the diary folder should be initialised.
///
/// # Arguments
///
/// * `opts` - The options passed by the user at runtime.
/// * `config` - The contents of the config file.
///
/// # Returns
///
/// Either the initialisation status, which provides the path to use, or a DiaryError
/// if the diary is already initialised somewhere.
fn establish_path(opts: &InitOptions, config: &Config) -> Result<InitStatus, DiaryError> {
    if config.diary_path() != &PathBuf::from("") {
        if config.diary_path().exists() {
            Err(DiaryError::ExistsElsewhere)
        } else {
            Ok(InitStatus::UseConfig(config.diary_path().to_path_buf()))
        }
    } else {
        let diary_path = opts.path.join("diary");
        if diary_path.exists() {
            return Err(DiaryError::ExistsHere);
        }
        Ok(InitStatus::UseOpt(diary_path))
    }
}

/// Initialises the diary folder, if possible.
///
/// # Arguments
///
/// * `opts` - The options passed by the user at runtime.
/// * `config` - The contents of the config file.
///
/// # Returns
///
/// Either the Path of the new diary folder or a DiaryError if there was an
/// issue with initialisation.
pub fn init(opts: &InitOptions, config: &Config) -> Result<PathBuf, DiaryError> {
    let init_status = establish_path(opts, config);
    let path = match init_status? {
        InitStatus::UseConfig(path) => {
            print!("It appears the config file already has a diary path set. ");
            println!("Creating a diary folder here: {:?}", path);
            path
        }
        InitStatus::UseOpt(path) => {
            println!("Creating a diary folder.");
            path
        }
    };
    let path = match create_dir_all(&path) {
        Ok(_) => path,
        Err(e) => return Err(DiaryError::from(e)), // uncovered.
    };

    if opts.git_repo {
        match Repository::init(&path) {
            Ok(_) => (),
            Err(e) => return Err(DiaryError::from(e)), // uncovered.
        };
    };
    Ok(path)
}

#[cfg(test)]
mod tests {
    use std::fs::create_dir_all;

    use super::{init, InitOptions};
    use crate::{config::Config, ops::testing};

    #[test]
    fn blank_config_valid_path() {
        let dir = testing::temp_path();
        let diary_dir = dir.join("diary");
        let opts = InitOptions {
            path: dir,
            prefix: None,
            git_repo: false,
        };
        let config = Config::default();

        init(&opts, &config).unwrap();

        assert!(diary_dir.exists());
    }

    #[test]
    fn blank_config_invalid_path() {
        let dir = testing::temp_path();
        let diary_dir = dir.join("diary");
        let opts = InitOptions {
            path: dir,
            prefix: None,
            git_repo: false,
        };
        let config = Config::default();
        create_dir_all(diary_dir).unwrap();

        init(&opts, &config).expect_err("No error produced.");
    }

    #[test]
    fn filled_config_non_existing_path() {
        let dir = testing::temp_path();
        let diary_dir = dir.join("diary");

        let config = Config::builder().diary_path(diary_dir.clone()).build();

        let opts = InitOptions {
            path: testing::temp_path(),
            prefix: None,
            git_repo: false,
        };

        init(&opts, &config).unwrap();

        assert!(diary_dir.exists());
    }

    #[test]
    fn filled_config_existing_path() {
        let dir = testing::temp_path();
        let diary_dir = dir.join("diary");
        let config = Config::builder().diary_path(diary_dir.clone()).build();

        let opts = InitOptions {
            path: testing::temp_path(),
            prefix: None,
            git_repo: false,
        };

        create_dir_all(diary_dir).unwrap();

        init(&opts, &config).expect_err("No error produced.");
    }

    #[test]
    fn blank_config_valid_path_git_repo() {
        let dir = testing::temp_path();
        let mut diary_dir = dir.join("diary");
        let opts = InitOptions {
            path: dir,
            prefix: None,
            git_repo: true,
        };
        let config = Config::default();

        init(&opts, &config).unwrap();

        diary_dir.push(".git");

        assert!(diary_dir.exists());
    }

    #[test]
    fn filled_config_non_existing_path_git_repo() {
        let dir = testing::temp_path();
        let mut diary_dir = dir.join("diary");
        let config = Config::builder().diary_path(diary_dir.clone()).build();

        let opts = InitOptions {
            path: testing::temp_path(),
            prefix: None,
            git_repo: true,
        };

        init(&opts, &config).unwrap();

        diary_dir.push(".git");

        assert!(diary_dir.exists());
    }

    #[test]
    fn filled_config_existing_path_git_repo() {
        let dir = testing::temp_path();
        let diary_dir = dir.join("diary");
        let config = Config::builder().diary_path(diary_dir.clone()).build();

        let opts = InitOptions {
            path: testing::temp_path(),
            prefix: None,
            git_repo: true,
        };

        create_dir_all(diary_dir).unwrap();

        init(&opts, &config).expect_err("No error produced.");
    }
}