use super::*;
use std::iter::Extend;

use log::trace;
use reqwest::{header, StatusCode, Url};
use serde::de::DeserializeOwned;

use crate::types::*;

/// A synchronous client for the crates.io API.
pub struct SyncClient {
    client: reqwest::Client,
    base_url: Url,
}

impl SyncClient {
    /// Instantiate a new synchronous API client.
    ///
    /// This will fail if the underlying http client could not be created.
    pub fn new() -> Self {
        Self {
            client: reqwest::Client::new(),
            base_url: Url::parse("https://crates.io/api/v1/").unwrap(),
        }
    }

    pub fn with_user_agent(user_agent: &str) -> Self {
        let mut headers = header::HeaderMap::new();
        headers.insert(
            header::USER_AGENT,
            header::HeaderValue::from_str(user_agent).unwrap(),
        );
        Self {
            client: reqwest::Client::builder()
                .default_headers(headers)
                .build()
                .unwrap(),
            base_url: Url::parse("https://crates.io/api/v1/").unwrap(),
        }
    }

    fn get<T: DeserializeOwned>(&self, url: Url) -> Result<T, Error> {
        trace!("GET {}", url);
        let mut res = {
            let res = self.client.get(url).send()?;

            if res.status() == StatusCode::NOT_FOUND {
                return Err(Error::NotFound);
            }
            res.error_for_status()?
        };

        let data: T = res.json()?;
        Ok(data)
    }

    /// Retrieve a summary containing crates.io wide information.
    pub fn summary(&self) -> Result<Summary, Error> {
        let url = self.base_url.join("summary").unwrap();
        self.get(url)
    }

    /// Retrieve information of a crate.
    ///
    /// If you require detailed information, consider using [full_crate]().
    pub fn get_crate(&self, name: &str) -> Result<CrateResponse, Error> {
        let url = self.base_url.join("crates/")?.join(name)?;
        self.get(url)
    }

    /// Retrieve download stats for a crate.
    pub fn crate_downloads(&self, name: &str) -> Result<Downloads, Error> {
        let url = self.base_url.join(&format!("crates/{}/downloads", name))?;
        self.get(url)
    }

    /// Retrieve the owners of a crate.
    pub fn crate_owners(&self, name: &str) -> Result<Vec<User>, Error> {
        let url = self.base_url.join(&format!("crates/{}/owners", name))?;
        let resp: Owners = self.get(url)?;
        Ok(resp.users)
    }

    /// Load all reverse dependencies of a crate.
    ///
    /// Note: Since the reverse dependency endpoint requires pagination, this
    /// will result in multiple requests if the crate has more than 100 reverse
    /// dependencies.
    pub fn crate_reverse_dependencies(&self, name: &str) -> Result<ReverseDependencies, Error> {
        let mut page = 1;
        let mut rdeps: ReverseDependenciesAsReceived;
        let mut tidy_rdeps = ReverseDependencies {dependencies: Vec::new(), meta: Meta {total:0}};

        loop {
            let url = self.base_url.join(&format!(
                "crates/{}/reverse_dependencies?per_page=100&page={}",
                name, page
            ))?;

            rdeps = self.get(url)?;

            tidy_rdeps.from_received(&rdeps);

            if !rdeps.dependencies.is_empty() {
                tidy_rdeps.meta = rdeps.meta;
                page += 1;
            } else {
                break;
            }
        }
        Ok(tidy_rdeps)
    }

    /// Retrieve the authors for a crate version.
    pub fn crate_authors(&self, name: &str, version: &str) -> Result<Authors, Error> {
        let url = self
            .base_url
            .join(&format!("crates/{}/{}/authors", name, version))?;
        let res: AuthorsResponse = self.get(url)?;
        Ok(Authors {
            names: res.meta.names,
            users: res.users,
        })
    }

    /// Retrieve the dependencies of a crate version.
    pub fn crate_dependencies(&self, name: &str, version: &str) -> Result<Vec<Dependency>, Error> {
        let url = self
            .base_url
            .join(&format!("crates/{}/{}/dependencies", name, version))?;
        let resp: Dependencies = self.get(url)?;
        Ok(resp.dependencies)
    }

    fn full_version(&self, version: Version) -> Result<FullVersion, Error> {
        let authors = self.crate_authors(&version.crate_name, &version.num)?;
        let deps = self.crate_dependencies(&version.crate_name, &version.num)?;

        let v = FullVersion {
            created_at: version.created_at,
            updated_at: version.updated_at,
            dl_path: version.dl_path,
            downloads: version.downloads,
            features: version.features,
            id: version.id,
            num: version.num,
            yanked: version.yanked,
            license: version.license,
            links: version.links,
            readme_path: version.readme_path,

            author_names: authors.names,
            authors: authors.users,
            dependencies: deps,
        };
        Ok(v)
    }

    /// Retrieve all available information for a crate, including download
    /// stats,  owners and reverse dependencies.
    ///
    /// The `all_versions` argument controls the retrieval of detailed version
    /// information.
    /// If false, only the data for the latest version will be fetched, if true,
    /// detailed information for all versions will be available.
    /// Note: Each version requires two extra requests.
    pub fn full_crate(&self, name: &str, all_versions: bool) -> Result<FullCrate, Error> {
        let resp = self.get_crate(name)?;
        let data = resp.crate_data;

        let dls = self.crate_downloads(name)?;
        let owners = self.crate_owners(name)?;
        let reverse_dependencies = self.crate_reverse_dependencies(name)?;

        let versions = if resp.versions.is_empty() {
            vec![]
        } else if all_versions {
            //let versions_res: Result<Vec<FullVersion>> = resp.versions
            resp.versions
                .into_iter()
                .map(|v| self.full_version(v))
                .collect::<Result<Vec<FullVersion>, Error>>()?
        } else {
            let v = self.full_version(resp.versions[0].clone())?;
            vec![v]
        };

        let full = FullCrate {
            id: data.id,
            name: data.name,
            description: data.description,
            license: versions[0].license.clone(),
            documentation: data.documentation,
            homepage: data.homepage,
            repository: data.repository,
            total_downloads: data.downloads,
            max_version: data.max_version,
            created_at: data.created_at,
            updated_at: data.updated_at,

            categories: resp.categories,
            keywords: resp.keywords,
            downloads: dls,
            owners,
            reverse_dependencies,
            versions,
        };
        Ok(full)
    }

    /// Retrieve a page of crates, optionally constrained by a query.
    ///
    /// If you want to get all results without worrying about paging,
    /// use [all_crates]().
    ///
    /// # Examples
    ///
    /// Retrieve the first page of results for the query "api", with 100 items
    /// per page and sorted alphabetically.
    ///
    /// ```
    /// # use crates_io_api::{SyncClient, ListOptions, Sort, Error};
    ///
    /// # fn f() -> Result<(), Error> {
    /// let client = SyncClient::new();
    /// client.crates(ListOptions{
    ///   sort: Sort::Alphabetical,
    ///   per_page: 100,
    ///   page: 1,
    ///   query: Some("api".to_string()),
    /// })?;
    /// # Ok(())
    /// # }
    /// ```
    ///
    pub fn crates(&self, spec: ListOptions) -> Result<CratesResponse, Error> {
        let mut url = self.base_url.join("crates")?;
        {
            let mut q = url.query_pairs_mut();
            q.append_pair("page", &spec.page.to_string());
            q.append_pair("per_page", &spec.per_page.to_string());
            q.append_pair("sort", spec.sort.to_str());
            if let Some(query) = spec.query {
                q.append_pair("q", &query);
            }
        }
        self.get(url)
    }

    /// Retrieve all crates, optionally constrained by a query.
    ///
    /// Note: This method fetches all pages of the result.
    /// This can result in a lot queries (100 results per query).
    pub fn all_crates(&self, query: Option<String>) -> Result<Vec<Crate>, Error> {
        let mut page = 1;
        let mut crates = Vec::new();
        loop {
            let res = self.crates(ListOptions {
                query: query.clone(),
                sort: Sort::Alphabetical,
                per_page: 100,
                page,
            })?;
            if !res.crates.is_empty() {
                crates.extend(res.crates);
                page += 1;
            } else {
                break;
            }
        }
        Ok(crates)
    }
}

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

    #[test]
    fn test_client() {
        let client = SyncClient::new();
        let summary = client.summary().unwrap();
        assert!(summary.most_downloaded.len() > 0);

        for item in &summary.most_downloaded[0..3] {
            let _ = client.full_crate(&item.name, false).unwrap();
        }
    }
}