//! Python wrapper for Brave's adblocking library, which is written in Rust.
#![deny(
    future_incompatible,
    nonstandard_style,
    rust_2018_idioms,
    missing_copy_implementations,
    trivial_casts,
    trivial_numeric_casts,
    unsafe_code,
    unused_qualifications
)]

use adblock::blocker::BlockerError as RustBlockerError;
use adblock::blocker::BlockerResult as RustBlockerResult;
use adblock::cosmetic_filter_cache::HostnameSpecificResources as RustHostnameSpecificResources;
use adblock::engine::Engine as RustEngine;
use pyo3::class::PyObjectProtocol;
use pyo3::exceptions::ValueError as PyValueError;
use pyo3::prelude::*;
use pyo3::PyErr;

use std::collections::HashMap;
use std::collections::HashSet;
use std::error::Error;
use std::fmt::{self, Display};
use std::fs;
use std::io::{Read, Write};

/// Brave's adblocking library in Python!
#[pymodule]
fn adblock(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
    m.add("__version__", env!("CARGO_PKG_VERSION"))?;
    m.add_class::<Engine>()?;
    m.add_class::<BlockerResult>()?;
    m.add_class::<HostnameSpecificResources>()?;
    Ok(())
}

/// The result of an ad-blocking check.
#[pyclass]
pub struct BlockerResult {
    #[pyo3(get)]
    pub matched: bool,
    /// Normally, Brave Browser returns `200 OK` with an empty body when
    /// `matched` is `True`, except if `explicit_cancel` is also `True`, in
    /// which case the request is cancelled.
    #[pyo3(get)]
    pub explicit_cancel: bool,
    /// Important is used to signal that a rule with the `important` option
    /// matched. An `important` match means that exceptions should not apply
    /// and no further checking is neccesary--the request should be blocked
    /// (empty body or cancelled).
    ///
    /// Brave Browser keeps seperate instances of Blocker for default lists
    /// and regional ones, so `important` here is used to correct behaviour
    /// between them: checking should stop instead of moving to the next
    /// instance iff an `important` rule matched.
    #[pyo3(get)]
    pub important: bool,
    /// Iff the blocker matches a rule which has the `redirect` option, as per
    /// [uBlock Origin's redirect syntax][1], the `redirect` is not `None`.
    /// The `redirect` field contains the body of the redirect to be injected.
    ///
    /// [1]: https://github.com/gorhill/uBlock/wiki/Static-filter-syntax#redirect
    #[pyo3(get)]
    pub redirect: Option<String>,
    /// Exception is not `None` when the blocker matched on an exception rule.
    /// Effectively this means that there was a match, but the request should
    /// not be blocked. It is a non-empty string if the blocker was initialized
    /// from a list of rules with debugging enabled, otherwise the original
    /// string representation is discarded to reduce memory use.
    #[pyo3(get)]
    pub exception: Option<String>,
    /// Filter--similarly to exception--includes the string representation of
    /// the rule when there is a match and debugging is enabled. Otherwise, on
    /// a match, it is not `None`.
    #[pyo3(get)]
    pub filter: Option<String>,
    /// The `error` field is only used to signal that there was an error in
    /// parsing the provided URLs when using the simpler
    /// `check_network_urls` method.
    #[pyo3(get)]
    pub error: Option<String>,
}

impl Into<BlockerResult> for RustBlockerResult {
    fn into(self) -> BlockerResult {
        BlockerResult {
            matched: self.matched,
            explicit_cancel: self.explicit_cancel,
            important: self.important,
            redirect: self.redirect,
            exception: self.exception,
            filter: self.filter,
            error: self.error,
        }
    }
}

#[pyproto]
impl PyObjectProtocol for BlockerResult {
    fn __repr__(&self) -> PyResult<String> {
        Ok(format!(
            "BlockerResult({}, {}, {}, {:?}, {:?}, {:?}, {:?})",
            self.matched,
            self.explicit_cancel,
            self.important,
            self.redirect,
            self.exception,
            self.filter,
            self.error
        ))
    }
}

#[derive(Debug, PartialEq, Eq, Copy, Clone)]
pub enum BlockerError {
    SerializationError,
    DeserializationError,
    OptimizedFilterExistence,
    BadFilterAddUnsupported,
    FilterExists,
}

impl Error for BlockerError {
    fn source(&self) -> Option<&(dyn Error + 'static)> {
        None
    }
}

impl Display for BlockerError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "{}",
            match self {
                Self::SerializationError => "Serialization error",
                Self::DeserializationError => "Deserialization error",
                Self::OptimizedFilterExistence => "Optimized filter exists",
                Self::BadFilterAddUnsupported => "Bad filter add unsupported",
                Self::FilterExists => "Filter exists",
            }
        )
    }
}

impl Into<PyErr> for BlockerError {
    fn into(self) -> PyErr {
        PyErr::new::<PyValueError, _>(format!("{:?}", self))
    }
}

impl Into<BlockerError> for RustBlockerError {
    fn into(self) -> BlockerError {
        match self {
            Self::SerializationError => BlockerError::SerializationError,
            Self::DeserializationError => BlockerError::DeserializationError,
            Self::OptimizedFilterExistence => BlockerError::OptimizedFilterExistence,
            Self::BadFilterAddUnsupported => BlockerError::BadFilterAddUnsupported,
            Self::FilterExists => BlockerError::FilterExists,
        }
    }
}

/// Contains cosmetic filter information intended to be injected into a
/// particular hostname.
#[pyclass]
pub struct HostnameSpecificResources {
    /// A set of any CSS selector on the page that should be hidden, i.e.
    /// styled as `{ display: none !important; }`.
    #[pyo3(get)]
    pub hide_selectors: HashSet<String>,
    /// A map of CSS selectors on the page to respective non-hide style rules,
    /// i.e. any required styles other than `display: none`.
    #[pyo3(get)]
    pub style_selectors: HashMap<String, Vec<String>>,
    /// A set of any class or id CSS selectors that should not have generic
    /// rules applied.
    // In practice, these should be passed to `class_id_stylesheet` and not
    // used otherwise.
    #[pyo3(get)]
    pub exceptions: HashSet<String>,
    /// Javascript code for any scriptlets that should be injected into the
    /// page.
    #[pyo3(get)]
    pub injected_script: String,
}

impl Into<HostnameSpecificResources> for RustHostnameSpecificResources {
    fn into(self) -> HostnameSpecificResources {
        HostnameSpecificResources {
            hide_selectors: self.hide_selectors,
            style_selectors: self.style_selectors,
            exceptions: self.exceptions,
            injected_script: self.injected_script,
        }
    }
}

#[pyproto]
impl PyObjectProtocol for HostnameSpecificResources {
    fn __repr__(&self) -> PyResult<String> {
        Ok(format!(
            "HostnameSpecificResources<{} hide selectors, {} style selectors, {} exceptions, injected_javascript={:?}>",
            self.hide_selectors.len(),
            self.style_selectors.len(),
            self.exceptions.len(),
            self.injected_script,
        ))
    }
}

/// The main object featured in this library. This object holds the adblocker's
/// state, and can be queried to see if a given request should be blocked or
/// not.
///
/// # Request types
/// A few of `Engine`'s methods have a field specifying a "resource type",
/// valid examples are:
/// * `beacon`
/// * `csp_report`
/// * `document`
/// * `font`
/// * `media`
/// * `object`
/// * `script`
/// * `stylesheet`
/// * and et cetera...
/// See the [Mozilla Web Documentation][1] for more info.
///
/// [1]: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/ResourceType
#[pyclass]
#[text_signature = "($self, network_filters=None, load_network=True, load_cosmetic=False, debug=False)"]
pub struct Engine {
    engine: RustEngine,
}

#[pymethods]
impl Engine {
    /// Create a new adblocking engine
    #[new]
    #[args(network_filters="None", load_network=true, load_cosmetic=false, debug=false)]
    pub fn new(
        network_filters: Option<Vec<String>>,
        load_network: bool,
        load_cosmetic: bool,
        debug: bool,
    ) -> Self {
        let filters = network_filters.unwrap_or(Vec::new());
        let engine = RustEngine::from_rules_parametrised(
            &filters,
            load_network,
            load_cosmetic,
            debug,
            true,
        );
        Self { engine }
    }

    /// Check if the given `url`—pointing to a resource of type `request_type`—
    /// is blocked, assuming the request is made from the given `source_url`.
    /// Returns an object of type `BlockerResult`.
    ///
    /// # Arguments
    /// * `url` - The URL of the request to check
    /// * `source_url` - The URL from where the request is made
    /// * `request_type` - The resource type that the request points to
    #[text_signature = "($self, url, source_url, request_type)"]
    pub fn check_network_urls(
        &self,
        url: &str,
        source_url: &str,
        request_type: &str,
    ) -> BlockerResult {
        let blocker_result = self
            .engine
            .check_network_urls(url, source_url, request_type);
        blocker_result.into()
    }

    /// Check if a request should be blocked based on the given parameters.
    ///
    /// # Arguments
    /// * `url` - The URL of the request to check
    /// * `hostname` - The given `url`'s hostname
    /// * `source_hostname` - The hostname of the source URL.
    /// * `request_type` - The resource type that the request points to
    /// * `third_party_request` - Is the given request to a third-party? Here,
    ///   `None` can be given and the engine will figure it out based on the
    ///   `hostname` and `source_hostname`.
    #[text_signature = "($self, url, hostname, source_hostname, requsest_type, third_party_request)"]
    pub fn check_network_urls_with_hostnames(
        &self,
        url: &str,
        hostname: &str,
        source_hostname: &str,
        request_type: &str,
        third_party_request: Option<bool>,
    ) -> BlockerResult {
        let blocker_result = self.engine.check_network_urls_with_hostnames(
            url,
            hostname,
            source_hostname,
            request_type,
            third_party_request,
        );
        blocker_result.into()
    }

    /// Check if a request should be blocked based on the given parameters.
    ///
    /// # Arguments
    /// * `url` - The URL of the request to check
    /// * `hostname` - The given `url`'s hostname
    /// * `source_hostname` - The hostname of the source URL.
    /// * `request_type` - The resource type that the request points to
    /// * `third_party_request` - Is the given request to a third-party? Here,
    ///   `None` can be given and the engine will figure it out based on the
    ///   `hostname` and `source_hostname`.
    /// * `previously_matched_rule` - Return a match as long as there are no
    ///    exceptions
    /// * `force_check_exceptions` - Check exceptions even if no other rule matches
    #[text_signature = "($self, url, hostname, source_hostname, request_type, \
        third_party_request, previously_matched_rule, force_check_exceptions)"]
    #[allow(clippy::too_many_arguments)]
    pub fn check_network_urls_with_hostnames_subset(
        &self,
        url: &str,
        hostname: &str,
        source_hostname: &str,
        request_type: &str,
        third_party_request: Option<bool>,
        previously_matched_rule: bool,
        force_check_exceptions: bool,
    ) -> BlockerResult {
        let blocker_result = self.engine.check_network_urls_with_hostnames_subset(
            url,
            hostname,
            source_hostname,
            request_type,
            third_party_request,
            previously_matched_rule,
            force_check_exceptions,
        );
        blocker_result.into()
    }

    /// Serialize this blocking engine to bytes. They can then be deserialized
    /// using `deserialize()` to get the same engine again.
    #[text_signature = "($self)"]
    pub fn serialize(&mut self) -> PyResult<Vec<u8>> {
        let result = self.engine.serialize();
        match result {
            Ok(x) => Ok(x),
            Err(error) => {
                let my_blocker_error: BlockerError = error.into();
                Err(my_blocker_error.into())
            }
        }
    }

    /// Serialize this blocking engine to a file. The file can then be
    /// deserialized using `deserialize_from_file()` to get the same engine
    /// again.
    #[text_signature = "($self, file)"]
    pub fn serialize_to_file(&mut self, file: &str) -> PyResult<()> {
        let data = self.serialize()?;
        let mut fd = fs::OpenOptions::new()
            .create(true)
            .truncate(true)
            .write(true)
            .open(file)?;
        fd.write_all(&data)?;
        Ok(())
    }

    /// Deserialize a blocking engine from bytes produced with `serialize()`.
    #[text_signature = "($self, serialized)"]
    pub fn deserialize(&mut self, serialized: &[u8]) -> PyResult<()> {
        let result = self.engine.deserialize(serialized);
        match result {
            Ok(_) => Ok(()),
            Err(error) => {
                let my_blocker_error: BlockerError = error.into();
                Err(my_blocker_error.into())
            }
        }
    }

    /// Deserialize a blocking engine from file produced with
    /// `serialize_to_file()`.
    #[text_signature = "($self, file)"]
    pub fn deserialize_from_file(&mut self, file: &str) -> PyResult<()> {
        let mut fd = fs::File::open(file)?;
        let mut data: Vec<u8> = Vec::new();
        fd.read_to_end(&mut data)?;
        self.deserialize(&data)
    }

    /// Add the contents of a block list file to the blocking engine.
    #[text_signature = "($self, filter_list)"]
    pub fn add_filter_list(&mut self, filter_list: &str) {
        self.engine.add_filter_list(filter_list);
    }

    /// Checks if the given filter exists in the blocking engine.
    #[text_signature = "($self, filter)"]
    pub fn filter_exists(&self, filter: &str) -> bool {
        self.engine.filter_exists(filter)
    }

    /// Enable the given tags
    #[text_signature = "($self, tags)"]
    pub fn tags_enable(&mut self, tags: Vec<&str>) {
        self.engine.tags_enable(&tags);
    }

    /// Disable the given tags
    #[text_signature = "($self, tags)"]
    pub fn tags_disable(&mut self, tags: Vec<&str>) {
        self.engine.tags_disable(&tags);
    }

    /// Check if the given tag exists
    #[text_signature = "($self, tag)"]
    pub fn tag_exists(&self, tag: &str) -> bool {
        self.engine.tag_exists(tag)
    }

    /// Returns a set of cosmetic filter resources required for a particular
    /// hostname. Once this has been called, all CSS ids and classes on a
    /// page should be passed to hidden_class_id_selectors to obtain any
    /// stylesheets consisting of generic rules.
    #[text_signature = "($self, hostname)"]
    pub fn hostname_cosmetic_resources(&self, hostname: &str) -> HostnameSpecificResources {
        self.engine.hostname_cosmetic_resources(hostname).into()
    }

    /// If any of the provided CSS classes or ids could cause a certain generic
    /// CSS hide rule (i.e. `{ display: none !important; }`) to be required, this
    /// method will return a list of CSS selectors corresponding to rules
    /// referencing those classes or ids, provided that the corresponding rules
    /// are not excepted.
    ///
    /// Exceptions should be passed directly from HostnameSpecificResources.
    #[text_signature = "($self, classes, ids, exceptions)"]
    pub fn hidden_class_id_selectors(
        &self,
        classes: Vec<String>,
        ids: Vec<String>,
        exceptions: HashSet<String>,
    ) -> PyResult<Vec<String>> {
        Ok(self
            .engine
            .hidden_class_id_selectors(&classes, &ids, &exceptions))
    }
}