//! This crate provides a client for interacting with the crossref-api
//!
//! [Crossref API docs](https://github.com/CrossRef/rest-api-doc)
//! `Crossref` - Crossref search API. The `Crossref` crate provides methods matching Crossref API routes:

//! * `works` - `/works` route
//! * `members` - `/members` route
//! * `prefixes` - `/prefixes` route
//! * `funders` - `/funders` route
//! * `journals` - `/journals` route
//! * `types` - `/types` route
//! * `agency` - `/works/{doi}/agency` get DOI minting agency
//!
//! ## Usage

//! ### Create a `Crossref` client:

//! ```edition2018
//! # use crossref::Crossref;
//! # fn run() -> Result<(), crossref::Error> {
//! let client = Crossref::builder().build()?;
//! # Ok(())
//! # }
//! ```
//!
//! If you have an [Authorization token for Crossref's Plus service](https://github.com/CrossRef/rest-api-doc#authorization-token-for-plus-service):
//!
//! ```edition2018
//! # use crossref::Crossref;
//! # fn run() -> Result<(), crossref::Error> {
//! let client = Crossref::builder()
//! .token("token")
//! .build()?;
//! # Ok(())
//! # }
//! ```
//!
//! Encouraged to use the **The Polite Pool**:
//!
//! [Good manners = more reliable service](https://github.com/CrossRef/rest-api-doc#good-manners--more-reliable-service)
//!
//! To get into Crossref's polite pool include a email address
//!
//! ```edition2018
//! # use crossref::Crossref;
//! # fn run() -> Result<(), crossref::Error> {
//! let client = Crossref::builder()
//!     .polite("polite@example.com")
//!     .token("your token")
//!     .build()?;
//! # Ok(())
//! # }
//! ```
//!
//! ### Constructing Queries
//! Not all components support queries and there are custom available parameters for each route that supports querying.
//! For each resource components that supports querying there exist a Query struct: `WorksQuery`, `MembersQuery`, `FundersQuery`. The `WorksQuery` also differs from the others by supporting [deep paging with cursors](https://github.com/CrossRef/rest-api-doc#deep-paging-with-cursors) and [field queries](https://github.com/CrossRef/rest-api-doc#works-field-queries).
//!
//! Otherwise creating queries works the same for all resource components:
//!
//! ```edition2018
//! # use crossref::*;
//! # fn run() -> Result<()> {
//! let query = WorksQuery::new("Machine Learning")
//! // field queries supported for `Works`
//! .field_query(FieldQuery::author("Some Author"))
//! // filters are specific for each resource component
//! .filter(WorksFilter::HasOrcid)
//! .order(Order::Asc)
//! .sort(Sort::Score);
//! # Ok(())
//! # }
//! ```
//!
//!
//! ### Get Records
//!
//! See [this table](https://github.com/CrossRef/rest-api-doc#resource-components) for a detailed overview of the major components.
//!
//! There are 3 available targets:
//!
//! * **standalone resource components**: `/works`, `/members`, etc. that return a list list of the corresponding items and can be specified with queries
//! * **Resource component with identifiers**: `/works/{doi}?<query>`,`/members/{member_id}?<query>`, etc. that returns a single item if found.
//! * **combined with the `works` route**: The works component can be appended to other resources: `/members/{member_id}/works?<query>` etc. that returns a list of matching `Work` items.
//!
//! This resembles in the enums of the resource components, eg. for `Members`:
//!
//! ```edition2018
//! # use crossref::query::*;
//! pub enum Members {
//!     /// target a specific member at `/members/{id}`
//!     Identifier(String),
//!     /// target all members that match the query at `/members?query...`
//!     Query(MembersQuery),
//!     /// target a `Work` for a specific member at `/members/{id}/works?query..`
//!     Works(WorksIdentQuery),
//! }
//! ```
//!
//! All options are supported by the client:
//!
//! **Single Item by DOI (ID)**
//!
//! Analogous methods exist for all resource components
//!
//! ```edition2018
//! # use crossref::*;
//! # fn run() -> Result<()> {
//! # let client = Crossref::builder().build()?;
//! let work = client.work("10.1037/0003-066X.59.1.29")?;
//!
//! let agency = client.work_agency("10.1037/0003-066X.59.1.29")?;
//!
//! let funder = client.funder("funder_id")?;
//!
//! let member = client.member("member_id")?;
//! # Ok(())
//! # }
//! ```
//!
//! **Query**
//!
//! ```edition2018
//! # use crossref::*;
//! # fn run() -> Result<()> {
//! # let client = Crossref::builder().build()?;
//! let query = WorksQuery::new("Machine Learning");
//!
//! // one page of the matching results
//! let works = client.works(query)?;
//! # Ok(())
//! # }
//! ```
//!
//! Alternatively insert a free form query term directly
//!
//! ```edition2018
//! # use crossref::*;
//! # fn run() -> Result<()> {
//! # let client = Crossref::builder().build()?;
//!
//! // one page of the matching results
//! let works = client.works("Machine Learning")?;
//! # Ok(())
//! # }
//! ```
//!
//! **Combining Routes with the `Works` route**
//!
//! For each resource component other than `Works` there exist methods to append a `WorksQuery` with the ID option `/members/{member_id}/works?<query>?`
//!
//! ```edition2018
//! # use crossref::*;
//! # fn run() -> Result<()> {
//! # let client = Crossref::builder().build()?;
//! let works = client.member_works( WorksQuery::new("machine learning")
//! .sort(Sort::Score).into_ident("member_id"))?;
//! # Ok(())
//! # }
//! ```
//!
//! This would be the same as using the [`Crossref::works`] method by supplying the combined type
//!
//! ```edition2018
//! # use crossref::*;
//! # fn run() -> Result<()> {
//! # let client = Crossref::builder().build()?;
//! let works = client.works(WorksQuery::new("machine learning")
//!     .sort(Sort::Score)
//!     .into_combined_query::<Members>("member_id"))?;
//! # Ok(())
//! # }
//! ```
//!
//! ** Deep paging for `Works` **
//! [Deep paging results](https://github.com/CrossRef/rest-api-doc#deep-paging-with-cursors)
//! Deep paging is supported for all queries, that return a list of `Work`, `WorkList`.
//! This function returns a new iterator over pages of `Work`, which is returned as bulk of items as a `WorkList` by crossref.
//! Usually a single page `WorkList` contains 20 items.
//!
//! # Example
//!
//! Iterate over all `Works` linked to search term `Machine Learning`
//!
//! ```edition2018
//! use crossref::{Crossref, WorksQuery, Work};
//! # fn run() -> Result<(), crossref::Error> {
//! let client = Crossref::builder().build()?;
//!
//! let all_works: Vec<Work> = client.deep_page(WorksQuery::new("Machine Learning")).flat_map(|x|x.items).collect();
//!
//! # Ok(())
//! # }
//! ```
//!
//! Which can be simplified to
//!
//! ```edition2018
//! use crossref::{Crossref, WorksQuery, Work};
//! # fn run() -> Result<(), crossref::Error> {
//! let client = Crossref::builder().build()?;
//!
//! let all_works: Vec<Work> = client.deep_page("Machine Learning").into_work_iter().collect();
//!
//! # Ok(())
//! # }
//! ```
//!
//!
//! # Example
//!
//! Iterate over all the pages (`WorkList`) of the funder with id `funder id` by using a combined query.
//! A single `WorkList` usually holds 20 `Work` items.
//!
//! ```edition2018
//! use crossref::{Crossref, Funders, WorksQuery, Work, WorkList};
//! # fn run() -> Result<(), crossref::Error> {
//! let client = Crossref::builder().build()?;
//!
//! let all_funder_work_list: Vec<WorkList> = client.deep_page(WorksQuery::default().into_combined_query::<Funders>("funder id")).collect();
//!
//! # Ok(())
//! # }
//! ```
//! # Example
//!
//! Iterate over all `Work` items of a specfic funder directly.
//!
//! ```edition2018
//! use crossref::{Crossref, Funders, WorksQuery, Work, WorkList};
//! # fn run() -> Result<(), crossref::Error> {
//! let client = Crossref::builder().build()?;
//!
//! let all_works: Vec<Work> = client.deep_page(WorksQuery::default()
//!         .into_combined_query::<Funders>("funder id"))
//!         .into_work_iter()
//!         .collect();
//!
//! # Ok(())
//! # }
//! ```

#![deny(warnings)]
#![deny(missing_docs)]
#![allow(unused)]

mod error;
/// provides types to construct a specific query
pub mod query;
/// provides the response types of the crossref api
pub mod response;

// TODO extract to optional feature?
/// content negotiation
pub mod cn;
/// textual data mining
pub mod tdm;

#[doc(inline)]
pub use self::error::{Error, Result};

#[doc(inline)]
pub use self::query::works::{
    FieldQuery, WorkListQuery, WorkResultControl, Works, WorksFilter, WorksIdentQuery, WorksQuery,
};

#[doc(inline)]
pub use self::query::{Component, CrossrefQuery, CrossrefRoute, Order, Sort};
pub use self::query::{Funders, Journals, Members, Prefixes, Type, Types};
pub use self::response::{
    CrossrefType, Funder, FunderList, Journal, JournalList, Member, MemberList, TypeList, Work,
    WorkAgency, WorkList,
};

pub(crate) use self::response::{Message, Response};

use crate::error::ErrorKind;
use crate::query::{FundersQuery, MembersQuery, ResourceComponent};
use crate::response::{MessageType, Prefix};
use reqwest::{self, Client};
use std::iter::FlatMap;

macro_rules! get_item {
    ($ident:ident, $value:expr, $got:expr) => {
        if let Some(msg) = $value {
            match msg {
                Message::$ident(item) => Ok(item),
                _ => Err(ErrorKind::UnexpectedItem {
                    expected: MessageType::$ident,
                    got: $got,
                }
                .into()),
            }
        } else {
            Err(ErrorKind::MissingMessage {
                expected: MessageType::$ident,
            }
            .into())
        }
    };
}

macro_rules! impl_combined_works_query {
    ($($name:ident  $component:ident,)*) => {
        $(
        /// Return one page of the components's `Work` that match the query
        ///
        pub fn $name(&self, ident: WorksIdentQuery) -> Result<WorkList> {
            let resp = self.get_response(&$component::Works(ident))?;
            get_item!(WorkList, resp.message, resp.message_type)
        })+
    };
}

/// Struct for Crossref search API methods
#[derive(Debug, Clone)]
pub struct Crossref {
    /// use another base url than `api.crossref.org`
    pub base_url: String,
    /// the reqwest client that handles the requests
    pub client: Client,
}

impl Crossref {
    const BASE_URL: &'static str = "https://api.crossref.org";

    /// Constructs a new `CrossrefBuilder`.
    ///
    /// This is the same as `Crossref::builder()`.
    pub fn builder() -> CrossrefBuilder {
        CrossrefBuilder::new()
    }

    // generate all functions to query combined endpoints
    impl_combined_works_query!(funder_works Funders, member_works Members,
    type_works Types, journal_works Journals, prefix_works Prefixes,);

    /// Transforms the `CrossrefQuery` in the request route and  executes the request
    ///
    /// # Errors
    ///
    /// If it was a bad url, the server will return `Resource not found` a `ResourceNotFound` error will be returned in this case
    /// Also fails if the json response body could be parsed into `Response`
    /// Fails if there was an error in reqwest executing the request [::reqwest::RequestBuilder::send]
    fn get_response<T: CrossrefQuery>(&self, query: &T) -> Result<Response> {
        let resp = self
            .client
            .get(&query.to_url(&self.base_url)?)
            .send()?
            .text()?;
        if resp.starts_with("Resource not found") {
            Err(ErrorKind::ResourceNotFound {
                resource: Box::new(query.clone().resource_component()),
            }
            .into())
        } else {
            Ok(serde_json::from_str(&resp)?)
        }
    }

    /// Return the `Work` items that match a certain query.
    ///
    /// To search only by query terms use the convenience query method [Crossref::query_works]
    ///
    /// # Example
    ///
    /// ```edition2018
    /// use crossref::{Crossref, WorksQuery, WorksFilter, FieldQuery};
    /// # fn run() -> Result<(), crossref::Error> {
    /// let client = Crossref::builder().build()?;
    ///
    /// let query = WorksQuery::new("Machine Learning")
    ///     .filter(WorksFilter::HasOrcid)
    ///     .order(crossref::Order::Asc)
    ///     .field_query(FieldQuery::author("Some Author"))
    ///     .sort(crossref::Sort::Score);
    ///
    /// let works = client.works(query)?;
    ///
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # Errors
    ///
    /// This method fails if the `works` element expands to a bad route `ResourceNotFound`
    /// Fails if the response body doesn't have `message` field `MissingMessage`.
    /// Fails if anything else than a `WorkList` is returned as message `UnexpectedItem`
    pub fn works<T: Into<WorkListQuery>>(&self, query: T) -> Result<WorkList> {
        let resp = self.get_response(&query.into())?;
        get_item!(WorkList, resp.message, resp.message_type)
    }

    /// Return the `Work` that is identified by  the `doi`.
    ///
    /// # Errors
    /// This method fails if the doi could not identified `ResourceNotFound`
    ///
    pub fn work(&self, doi: &str) -> Result<Work> {
        let resp = self.get_response(&Works::Identifier(doi.to_string()))?;
        get_item!(Work, resp.message, resp.message_type).map(|x| *x)
    }

    /// [Deep paging results](https://github.com/CrossRef/rest-api-doc#deep-paging-with-cursors)
    /// Deep paging is supported for all queries, that return a list of `Work`, `WorkList`.
    /// This function returns a new iterator over pages of `Work`, which is returned as bulk of items as a `WorkList` by crossref.
    /// Usually a single page `WorkList` contains 20 items.
    ///
    /// # Example
    ///
    /// Iterate over all `Works` linked to search term `Machine Learning`
    ///
    /// ```edition2018
    /// use crossref::{Crossref, WorksQuery, Work};
    /// # fn run() -> Result<(), crossref::Error> {
    /// let client = Crossref::builder().build()?;
    ///
    /// let all_works: Vec<Work> = client.deep_page(WorksQuery::new("Machine Learning")).flat_map(|x|x.items).collect();
    ///
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # Example
    ///
    /// Iterate over all the pages (`WorkList`) of the funder with id `funder id` by using a combined query.
    /// A single `WorkList` usually holds 20 `Work` items.
    ///
    /// ```edition2018
    /// use crossref::{Crossref, Funders, WorksQuery, Work, WorkList};
    /// # fn run() -> Result<(), crossref::Error> {
    /// let client = Crossref::builder().build()?;
    ///
    /// let all_funder_work_list: Vec<WorkList> = client.deep_page(WorksQuery::default().into_combined_query::<Funders>("funder id")).collect();
    ///
    /// # Ok(())
    /// # }
    /// ```
    /// # Example
    ///
    /// Iterate over all `Work` items of a specfic funder directly.
    ///
    /// ```edition2018
    /// use crossref::{Crossref, Funders, WorksQuery, Work, WorkList};
    /// # fn run() -> Result<(), crossref::Error> {
    /// let client = Crossref::builder().build()?;
    ///
    /// let all_works: Vec<Work> = client.deep_page(WorksQuery::default()
    ///         .into_combined_query::<Funders>("funder id"))
    ///         .into_work_iter()
    ///         .collect();
    ///
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # Example
    ///
    /// Alternatively deep page without an iterator by handling the cursor directly
    ///
    /// ```edition2018
    /// use crossref::{Crossref, WorksQuery, WorksFilter};
    /// # fn run() -> Result<(), crossref::Error> {
    /// let client = Crossref::builder().build()?;
    ///
    /// // request a next-cursor first
    /// let query = WorksQuery::new("Machine Learning")
    ///     .new_cursor();
    ///
    /// let works = client.works(query.clone())?;
    ///
    /// // this continues from where this first response stopped
    /// // if no more work items are available then a empty list will be returned
    /// let deep_works = client.works(
    ///     query.next_cursor(&works.next_cursor.unwrap())
    /// )?;
    /// # Ok(())
    /// # }
    /// ```
    ///
    pub fn deep_page<T: Into<WorkListQuery>>(&self, query: T) -> WorkListIterator {
        WorkListIterator {
            query: query.into(),
            client: self,
            index: 0,
            finish_next_iteration: false,
        }
    }

    /// Return the `Agency` that registers the `Work` identified by  the `doi`.
    ///
    /// # Errors
    /// This method fails if the doi could not identified `ResourceNotFound`
    ///
    pub fn work_agency(&self, doi: &str) -> Result<WorkAgency> {
        let resp = self.get_response(&Works::Agency(doi.to_string()))?;
        get_item!(WorkAgency, resp.message, resp.message_type)
    }

    /// Return the matching `Funders` items.
    pub fn funders(&self, funders: FundersQuery) -> Result<FunderList> {
        let resp = self.get_response(&Funders::Query(funders))?;
        get_item!(FunderList, resp.message, resp.message_type)
    }

    /// Return the `Funder` for the `id`
    pub fn funder(&self, id: &str) -> Result<Funder> {
        let resp = self.get_response(&Funders::Identifier(id.to_string()))?;
        get_item!(Funder, resp.message, resp.message_type).map(|x| *x)
    }

    /// Return the matching `Members` items.
    pub fn members(&self, members: MembersQuery) -> Result<MemberList> {
        let resp = self.get_response(&Members::Query(members))?;
        get_item!(MemberList, resp.message, resp.message_type)
    }

    /// Return the `Member` for the `id`
    pub fn member(&self, member_id: &str) -> Result<Member> {
        let resp = self.get_response(&Members::Identifier(member_id.to_string()))?;
        get_item!(Member, resp.message, resp.message_type).map(|x| *x)
    }

    /// Return the `Prefix` for the `id`
    pub fn prefix(&self, id: &str) -> Result<Prefix> {
        let resp = self.get_response(&Prefixes::Identifier(id.to_string()))?;
        get_item!(Prefix, resp.message, resp.message_type)
    }
    /// Return a specific `Journal`
    pub fn journal(&self, id: &str) -> Result<Journal> {
        let resp = self.get_response(&Journals::Identifier(id.to_string()))?;
        get_item!(Journal, resp.message, resp.message_type).map(|x| *x)
    }

    /// Return all available `Type`
    pub fn types(&self) -> Result<TypeList> {
        let resp = self.get_response(&Types::All)?;
        get_item!(TypeList, resp.message, resp.message_type)
    }

    /// Return the `Type` for the `id`
    pub fn type_(&self, id: &Type) -> Result<CrossrefType> {
        let resp = self.get_response(&Types::Identifier(id.id().to_string()))?;
        get_item!(Type, resp.message, resp.message_type)
    }

    /// Get a random set of DOIs
    ///
    /// # Example
    ///
    /// ```edition2018
    /// use crossref::Crossref;
    /// # fn run() -> Result<(), crossref::Error> {
    /// # let client = Crossref::builder().build()?;
    /// // this will return 10 random dois from the crossref api
    /// let random_dois = client.random_dois(10)?;
    /// # Ok(())
    /// # }
    /// ```
    pub fn random_dois(&self, len: usize) -> Result<Vec<String>> {
        self.works(WorksQuery::random(len))
            .map(|x| x.items.into_iter().map(|x| x.doi).collect())
    }
}

/// A `CrossrefBuilder` can be used to create `Crossref` with additional config.
///
/// # Example
///
/// ```edition2018
/// use crossref::Crossref;
/// # fn run() -> Result<(), crossref::Error> {
///
/// let client = Crossref::builder()
///     .polite("polite@example.com")
///     .token("your token")
///     .build()?;
/// # Ok(())
/// # }
/// ```
#[derive(Default)]
pub struct CrossrefBuilder {
    /// [Good manners = more reliable service.](https://github.com/CrossRef/rest-api-doc#good-manners--more-reliable-service)
    ///
    /// will add a `User-Agent` header by default with with the `email` email.
    /// crossref can contact you if your script misbehaves
    /// this will get you directed to the "polite pool"
    user_agent: Option<String>,
    /// the token for the Crossref Plus service will be included as `Authorization` header
    /// This token will ensure that said requests get directed to a pool of machines that are reserved for "Plus" SLA users.
    plus_token: Option<String>,
    /// use a different base url than `Crossref::BASE_URL` https://api.crossref.org
    base_url: Option<String>,
}

impl CrossrefBuilder {
    /// Constructs a new `CrossrefBuilder`.
    ///
    /// This is the same as `Crossref::builder()`.
    pub fn new() -> CrossrefBuilder {
        CrossrefBuilder::default()
    }

    /// be polite and set your email as `User-Agent`
    /// will get you in the polite pool of crossref
    pub fn polite(mut self, email: &str) -> Self {
        self.user_agent = Some(format!("mailto:{}", email));
        self
    }

    /// set the user agent directly
    pub fn user_agent(mut self, user_agent: &str) -> Self {
        self.user_agent = Some(user_agent.to_string());
        self
    }

    /// set a crossref plus service  API token
    pub fn token(mut self, token: &str) -> Self {
        self.plus_token = Some(token.to_string());
        self
    }

    /// Returns a `Crossref` that uses this `CrossrefBuilder` configuration.
    /// # Errors
    ///
    /// This will fail if TLS backend cannot be initialized see [reqwest::ClientBuilder::build]
    pub fn build(self) -> Result<Crossref> {
        use reqwest::header;
        let mut headers = header::HeaderMap::new();
        if let Some(agent) = &self.user_agent {
            headers.insert(
                header::USER_AGENT,
                header::HeaderValue::from_str(agent).map_err(|_| ErrorKind::Config {
                    msg: format!("failed to create User Agent header for `{}`", agent),
                })?,
            );
        }
        if let Some(token) = &self.plus_token {
            headers.insert(
                header::AUTHORIZATION,
                header::HeaderValue::from_str(token).map_err(|_| ErrorKind::Config {
                    msg: format!("failed to create AUTHORIZATION header for `{}`", token),
                })?,
            );
        }
        let client = reqwest::Client::builder()
            .default_headers(headers)
            .build()
            .map_err(|_| ErrorKind::Config {
                msg: "failed to initialize TLS backend".to_string(),
            })?;

        Ok(Crossref {
            base_url: self
                .base_url
                .unwrap_or_else(|| Crossref::BASE_URL.to_string()),
            client,
        })
    }
}

/// Allows iterating of deep page work request
pub struct WorkListIterator<'a> {
    /// the query
    query: WorkListQuery,
    /// performs each request
    client: &'a Crossref,
    /// stores how many results already retrieved
    index: usize,
    /// whether the iterator should finish next iteration
    finish_next_iteration: bool,
}
impl<'a> WorkListIterator<'a> {
    /// convenience method to create a `WorkIterator`
    pub fn into_work_iter(self) -> impl Iterator<Item = Work> + 'a {
        self.flat_map(|x| x.items)
    }
}

impl<'a> Iterator for WorkListIterator<'a> {
    type Item = WorkList;

    fn next(&mut self) -> Option<Self::Item> {
        if self.finish_next_iteration {
            return None;
        }

        {
            let control = &mut self.query.query_mut().result_control;

            // if no result control is set, set a new cursor
            if control.is_none() {
                *control = Some(WorkResultControl::new_cursor());
            }
        }

        let resp = self.client.get_response(&self.query);
        if let Ok(resp) = resp {
            let worklist: Result<WorkList> = get_item!(WorkList, resp.message, resp.message_type);
            if let Ok(worklist) = worklist {
                if let Some(cursor) = &worklist.next_cursor {
                    match &mut self.query.query_mut().result_control {
                        Some(WorkResultControl::Cursor { token, .. }) => {
                            // use the received cursor token in next iteration
                            *token = Some(cursor.clone())
                        }
                        Some(WorkResultControl::Standard(_)) => {
                            // standard result control was set, don't deep page and return next iteration
                            self.finish_next_iteration = true;
                        }
                        _ => (),
                    }
                } else {
                    // no cursor received, end next iteration
                    self.finish_next_iteration = true;
                }

                if worklist.items.is_empty() {
                    None
                } else {
                    Some(worklist)
                }
            } else {
                // failed to deserialize response into `WorkList`
                None
            }
        } else {
            // no response received
            None
        }
    }
}