use std::{fmt, path::PathBuf};

use anyhow::Context;
use diesel::{Connection, SqliteConnection};
use diesel_migrations::MigrationHarness;
use schist_models::migrations::MIGRATIONS;

pub struct DatabaseConnection {
    pub connection: diesel::SqliteConnection,
    pub file_path: PathBuf,
}

impl DatabaseConnection {
    pub fn establish(file_path: PathBuf) -> DatabaseConnectionResult {
        DatabaseConnectionResult {
            connection: Self::establish_sqlite_connection(&file_path),
            file_path: file_path,
        }
    }

    fn establish_sqlite_connection(file_path: &PathBuf) -> anyhow::Result<SqliteConnection> {
        let file_path_str = file_path
            .to_str()
            .with_context(|| format!("Failed to get database path from {:?}", file_path))?;
        let mut connection = diesel::SqliteConnection::establish(&file_path_str)
            .with_context(|| format!("Failed to connect to database at {}", file_path_str))?;
        connection
            .run_pending_migrations(MIGRATIONS)
            .map_err(anyhow::Error::from_boxed)
            .with_context(|| {
                format!(
                    "Failed to run pending migrations on database at {}",
                    file_path_str
                )
            })?;
        Ok(connection)
    }
}

impl fmt::Debug for DatabaseConnection {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SqliteConnection")
            .field("file_path", &self.file_path)
            .finish()
    }
}

pub struct DatabaseConnectionResult {
    pub connection: anyhow::Result<SqliteConnection>,
    pub file_path: PathBuf,
}

impl DatabaseConnectionResult {
    pub fn ok(self) -> Result<DatabaseConnection, (PathBuf, anyhow::Error)> {
        self.try_into()
    }
}

impl TryFrom<DatabaseConnectionResult> for DatabaseConnection {
    type Error = (PathBuf, anyhow::Error);

    fn try_from(result: DatabaseConnectionResult) -> Result<Self, Self::Error> {
        result
            .connection
            .map(|connection| DatabaseConnection {
                connection,
                file_path: result.file_path.clone(),
            })
            .map_err(|err| (result.file_path, err))
    }
}