/*
Copyright (C) 2021 Kunal Mehta <legoktm@debian.org>

This program 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.

This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

//! A MediaWiki bot and tool framework
//!
//! `mwbot` aims to provide a batteries-included framework for building bots
//! and tools for MediaWiki wikis. It builds on top of the [mwapi](https://docs.rs/mwapi)
//! and [parsoid](https://docs.rs/parsoid) crates, which offer lower-level APIs.
//!
//! ## Quickstart
//! ### Configuration
//! Create a `~/.config/mwbot.toml` file with the following structure:
//! ```toml
//! api_url = "https://en.wikipedia.org/w/api.php"
//! rest_url = "https://en.wikipedia.org/api/rest_v1"
//! ```
//!
//! If want to authenticate, add an auth section:
//! ```toml
//! [auth]
//! username = "Example"
//! oauth2_token = "[...]"
//! ```
//! See [the OAuth documentation](https://www.mediawiki.org/wiki/OAuth/For_Developers#OAuth_2)
//! for how to get an OAuth 2 token. Using an [owner-only consumer](https://www.mediawiki.org/wiki/OAuth/Owner-only_consumers#OAuth_2)
//! is the easiest way to do so.
//!
//! ### Reading a page
//! ```
//! # async fn demo() -> mwbot::Result<()> {
//! # use parsoid::prelude::*;
//! let bot = mwbot::Bot::from_default_config().await.unwrap();
//! let page = bot.page("Rust (programming language)")?;
//! let html = page.html().await?.into_mutable();
//! // The lead section is the second p tag in the first section
//! let lead = html.select("section > p")[1].text_contents();
//! assert!(lead.starts_with("Rust is a multi-paradigm, general-purpose programming language"));
//! # Ok(())
//! # }
//! ```
//! Using `Bot::from_default_config()` will look in the current directory
//! for `mwbot.toml` before looking in the user's config directory. A
//! custom path can be specified by using `Bot::from_config(...)`.
//!
//! ### Editing a page
//! ```
//! # async fn demo() -> mwbot::Result<()> {
//! # use mwbot::SaveOptions;
//! let bot = mwbot::Bot::from_default_config().await.unwrap();
//! let page = bot.page("Project:Sandbox")?;
//! let wikitext = "This is a test edit!";
//! page.save(wikitext, &SaveOptions::summary("test edit!")).await?;
//! # Ok(())
//! # }
//! ```
//! `Page.save()` accepts both HTML and wikitext and supports the [`{{nobots}}`](https://en.wikipedia.org/wiki/Template:Bots)
//! exclusion mechanism, among other features.
//!
//! ### Next steps
//! Try using one of the offered [page generators](./generators/index.html) to fetch and operate on
//! multiple pages.
//!
//! ## Contributing
//! `mwbot` is the flagship crate of the [`mwbot-rs` project](https://www.mediawiki.org/wiki/Mwbot-rs).
//! We're always looking for new contributors, please [reach out](https://www.mediawiki.org/wiki/Mwbot-rs#Contributing)
//! if you're interested!
#![deny(clippy::all)]
#![deny(rustdoc::all)]
#![cfg_attr(docs, feature(doc_cfg))]

mod builder;
mod config;
mod edit;
mod error;
#[cfg(feature = "upload")]
#[cfg_attr(docs, doc(cfg(feature = "upload")))]
pub mod file;
#[cfg(feature = "generators")]
#[cfg_attr(docs, doc(cfg(feature = "generators")))]
pub mod generators;
mod logging;
mod page;
mod siteinfo;
#[cfg(unix)]
mod unix;
#[cfg(feature = "upload")]
#[cfg_attr(docs, doc(cfg(feature = "upload")))]
pub mod upload;
mod utils;

pub use error::{config::ConfigError, Error};
pub use mwapi::Client as ApiClient;
use mwapi::ErrorFormat;
pub use mwtimestamp as timestamp;
use mwtitle::{Title, TitleCodec};
use once_cell::sync::OnceCell;
pub use parsoid;
use std::{path::Path, sync::Arc};
use tokio::{sync::Mutex, time};
use tracing::{debug, info};
pub type Result<T, E = Error> = std::result::Result<T, E>;
pub use builder::Builder;
pub use edit::SaveOptions;
pub use logging::init as init_logging;
pub use page::Page;

use parsoid::prelude::*;

/// Main bot class
#[derive(Clone, Debug)]
pub struct Bot {
    api: ApiClient,
    parsoid: ParsoidClient,
    state: BotState,
    config: Arc<BotConfig>,
}

/// Static, read-only settings
#[derive(Clone, Debug)]
struct BotConfig {
    // TODO: figure out something better than this
    username: Option<String>,
    codec: TitleCodec,
    /// Whether edits should be marked as bot (default: true)
    mark_as_bot: bool,
    /// Whether to respect {{nobots}} (default: true)
    respect_nobots: bool,
}

/// Dynamic state
#[derive(Clone, Debug)]
struct BotState {
    save_timer: Option<Arc<Mutex<time::Interval>>>,
}

impl Bot {
    /// Build a `Bot` instance programmatically.
    pub fn builder(api_url: String, rest_url: String) -> Builder {
        Builder::new(api_url, rest_url)
    }

    /// Load Bot configuration from a default location, first look at
    /// `mwbot.toml` in the current directory, otherwise look in the
    /// platform's config directory:
    ///
    /// * Linux: `$XDG_CONFIG_HOME` or `$HOME/.config`
    /// * macOS: `$HOME/Library/Application Support`
    /// * Windows: `{FOLDERID_RoamingAppData}`
    pub async fn from_default_config() -> Result<Self, ConfigError> {
        let path = {
            let first = Path::new("mwbot.toml");
            if first.exists() {
                first.to_path_buf()
            } else {
                dirs::config_dir()
                    .expect("Cannot find config directory")
                    .join("mwbot.toml")
            }
        };
        Self::from_path(&path).await
    }

    /// Load Bot configuration from the specified path.
    pub async fn from_path(path: &Path) -> Result<Self, ConfigError> {
        debug!("Reading config from {:?}", path);
        let config: config::Config =
            toml::from_str(&std::fs::read_to_string(path)?)?;
        // Check file permissions if there are credentials
        if config.auth.is_some() {
            check_file_permissions(path)?;
        }
        Self::from_config(config).await
    }

    async fn from_config(config: config::Config) -> Result<Self, ConfigError> {
        let mut api = ApiClient::builder(&config.api_url)
            .set_maxlag(config.general.maxlag.unwrap_or(5))
            .set_errorformat(ErrorFormat::Wikitext);
        if let Some(limit) = config.general.retry_limit {
            api = api.set_retry_limit(limit);
        }
        let mut user_agent = vec![];
        if let Some(extra) = config.general.user_agent {
            user_agent.push(extra);
        }
        // FIXME: do better
        let mut username = None;
        if let Some(auth) = config.auth {
            match &auth {
                config::Auth::BotPassword { username, password } => {
                    info!("Logging in as {} with password", username);
                    api = api.set_botpassword(username, password);
                }
                config::Auth::OAuth2 {
                    username,
                    oauth2_token,
                } => {
                    info!("Logging in as {} with OAuth2 token", username);
                    api = api.set_oauth2_token(oauth2_token);
                }
            }
            let normalized = normalize_username(auth.username());
            user_agent.push(format!("User:{}", &normalized));
            username = Some(normalized);
        }
        user_agent.push(format!("mwbot-rs/{}", env!("CARGO_PKG_VERSION")));
        let user_agent = user_agent.join(" ");
        let save_delay = config.edit.save_delay.unwrap_or(10);
        let save_timer = if save_delay > 0 {
            let mut interval =
                time::interval(time::Duration::from_secs(save_delay));
            interval.set_missed_tick_behavior(time::MissedTickBehavior::Delay);
            Some(Arc::new(Mutex::new(interval)))
        } else {
            None
        };
        let api = api
            .set_user_agent(&user_agent)
            .build()
            .await
            .map_err(Error::from)?;
        let siteinfo = siteinfo::get_siteinfo(&api).await?;
        let http = api.http_client().clone();
        Ok(Self {
            api,
            parsoid: ParsoidClient::new_with_client(&config.rest_url, http),
            config: Arc::new(BotConfig {
                username,
                codec: TitleCodec::from_site_info(siteinfo)
                    .map_err(Error::from)?,
                mark_as_bot: config.edit.mark_as_bot.unwrap_or(true),
                respect_nobots: config.edit.respect_nobots.unwrap_or(true),
            }),
            state: BotState { save_timer },
        })
    }

    /// Get a reference to the underlying [`mwapi::Client`](https://docs.rs/mwapi/latest/mwapi/struct.Client.html)
    /// to make arbitrary API requests
    pub fn api(&self) -> &ApiClient {
        &self.api
    }

    /// Get a reference to the underlying [`parsoid::Client`](https://docs.rs/parsoid/latest/parsoid/struct.Client.html)
    /// to make arbitrary Parsoid API requests
    pub fn parsoid(&self) -> &ParsoidClient {
        &self.parsoid
    }

    /// Get a reference to the internal [`mwtitle::TitleCodec`](https://docs.rs/mwtitle/latest/mwtitle/struct.TitleCodec.html)
    /// to parse and construct arbitrary titles.
    pub fn title_codec(&self) -> &TitleCodec {
        &self.config.codec
    }

    /// Get a `Page` on this wiki. The specified title should be a full title,
    /// including namespace. This does some validation on the
    /// provided input.
    pub fn page(&self, title: &str) -> Result<Page> {
        let title = self.config.codec.new_title(title)?.remove_fragment();
        self.page_from_title(title)
    }

    /// Get a `Page` on this wiki using information from a database row.
    ///
    /// The provided input will be validated and may return an
    /// error if invalid.
    pub fn page_from_database(
        &self,
        namespace: i32,
        dbkey: &str,
    ) -> Result<Page> {
        let title = self
            .config
            .codec
            .new_title_from_database(namespace, dbkey)?
            .remove_fragment();
        self.page_from_title(title)
    }

    /// Get a `Page` for a given [`Title`](https://docs.rs/mwtitle/latest/mwtitle/struct.Title.html)
    pub fn page_from_title(&self, title: Title) -> Result<Page> {
        if !title.is_local_page() {
            return Err(Error::InvalidPage);
        }
        Ok(Page {
            bot: self.clone(),
            title,
            title_text: Default::default(),
            info: Default::default(),
            baserevid: Default::default(),
        })
    }

    /// Get a `Page` on this wiki using page id.
    ///
    /// The provided input will be validated and may return an
    /// error if invalid.
    pub async fn page_from_id(&self, page_id: u64) -> Result<Page> {
        let mut resp: page::InfoResponse = mwapi_responses::query_api(
            &self.api,
            [("pageids", page_id.to_string())],
        )
        .await?;
        let info = resp
            .query
            .pages
            .pop()
            .expect("API response returned 0 pages");
        let title = self.config.codec.new_title(&info.title)?.remove_fragment();
        if !title.is_local_page() {
            return Err(Error::InvalidPage);
        }
        Ok(Page {
            bot: self.clone(),
            title,
            title_text: Default::default(),
            info: Arc::new(info.clone().into()),
            baserevid: info
                .lastrevid
                .map_or_else(OnceCell::new, OnceCell::with_value),
        })
    }
}

/// Verify file permissions are not obviously misconfigured:
/// * If the file is owned by the current user, it should only be readable to
///   that user
/// * If the file is owned by another user, it should not be world readable
///
/// TODO: support [extended ACLs](https://wiki.archlinux.org/title/Access_Control_Lists)
#[cfg(unix)]
fn check_file_permissions(path: &Path) -> Result<(), ConfigError> {
    use std::os::unix::fs::{MetadataExt, PermissionsExt};
    let metadata = std::fs::metadata(path)?;
    let mode = metadata.permissions().mode();
    let owner = metadata.uid();
    let current_user = unix::get_current_uid();
    let group_readable = mode & 0o40 != 0;
    let world_readable = mode & 0o4 != 0;
    if owner == current_user {
        // We own the file, so it should be only readable to us
        if group_readable || world_readable {
            Err(ConfigError::ReadableConfig(mode))
        } else {
            Ok(())
        }
    } else {
        // Someone else owns the file, so just check it's not world readable
        if world_readable {
            Err(ConfigError::WorldReadableConfig(mode))
        } else {
            Ok(())
        }
    }
}

#[cfg(not(unix))]
fn check_file_permissions(_path: &Path) -> Result<(), ConfigError> {
    // XXX: Implement this for other platforms
    Ok(())
}

// TODO: Can we reuse TitleCodec here?
fn normalize_username(original: &str) -> String {
    // MW normalization, underscores to spaces
    let name = original.replace('_', " ");
    // If it's a bot password, strip the @<name> part
    match name.split_once('@') {
        Some((name, _)) => name.to_string(),
        None => name,
    }
}

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

    pub(crate) fn is_authenticated() -> bool {
        std::env::var("MWAPI_TOKEN").is_ok()
    }

    pub(crate) async fn testwp() -> Bot {
        let username = std::env::var("MWAPI_USERNAME");
        let token = std::env::var("MWAPI_TOKEN");
        let auth = if let (Ok(username), Ok(oauth2_token)) = (username, token) {
            Some(config::Auth::OAuth2 {
                username,
                oauth2_token,
            })
        } else {
            None
        };

        Bot::from_config(config::Config {
            api_url: "https://test.wikipedia.org/w/api.php".to_string(),
            rest_url: "https://test.wikipedia.org/api/rest_v1".to_string(),
            auth,
            general: Default::default(),
            edit: Default::default(),
        })
        .await
        .unwrap()
    }

    fn assert_send_sync<T: Send + Sync>() {}

    /// Assert all these types are Send + Sync
    #[test]
    fn test_send_sync() {
        assert_send_sync::<Bot>();
        assert_send_sync::<Page>();
    }

    #[test]
    fn test_normalize_username() {
        assert_eq!(&normalize_username("Foo"), "Foo");
        assert_eq!(&normalize_username("Foo_bar"), "Foo bar");
        assert_eq!(&normalize_username("Foo@bar"), "Foo");
    }

    #[tokio::test]
    async fn test_get_api() {
        let bot = testwp().await;
        // No errors
        bot.api().get_value(&[("action", "query")]).await.unwrap();
    }

    #[tokio::test]
    async fn test_page() {
        let bot = testwp().await;
        let page = bot.page("Example").unwrap();
        assert_eq!(page.title(), "Example");
        assert_eq!(page.namespace(), 0);
        let page = bot.page_from_database(1, "Example").unwrap();
        assert_eq!(page.title(), "Talk:Example");
        assert_eq!(page.namespace(), 1);
        let error = bot.page("mw:External").unwrap_err();
        assert!(matches!(error, Error::InvalidPage));
    }

    #[tokio::test]
    async fn test_page_from_id() {
        let bot = testwp().await;
        let page = bot.page_from_id(122863).await.unwrap();
        assert_eq!(page.title(), "Mwbot-rs");
        assert_eq!(page.namespace(), 0);
        let page = bot.page_from_id(153569).await.unwrap();
        assert_eq!(page.title(), "Talk:Mwbot-rs");
        assert_eq!(page.namespace(), 1);
    }

    #[tokio::test]
    #[ignore] // flaky, see T341906
    async fn test_user_agent() {
        let bot = testwp().await;
        let version = env!("CARGO_PKG_VERSION");
        let resp: serde_json::Value = bot
            .api()
            .http_client()
            .get("https://httpbin.org/user-agent")
            .send()
            .await
            .unwrap()
            .json()
            .await
            .unwrap();
        let user_agent = resp["user-agent"].as_str().unwrap();
        match &bot.config.username {
            Some(username) => {
                assert_eq!(
                    user_agent,
                    &format!("User:{username} mwbot-rs/{version}")
                );
            }
            None => {
                assert_eq!(user_agent, &format!("mwbot-rs/{version}"));
            }
        }
    }

    /// T333423 regression test
    #[tokio::test]
    async fn test_zero_save_delay() {
        Bot::builder(
            "https://test.wikipedia.org/w/api.php".to_string(),
            "https://test.wikipedia.org/api/rest_v1".to_string(),
        )
        .set_save_delay(0)
        .build()
        .await
        .unwrap();
    }
}