use crate::{Cache, Repo, RepoType};
use indicatif::{ProgressBar, ProgressStyle};
use std::collections::HashMap;
// use reqwest::{
//     blocking::Agent,
//     header::{
//         HeaderMap, HeaderName, HeaderValue, InvalidHeaderValue, ToStrError, AUTHORIZATION,
//         CONTENT_RANGE, LOCATION, RANGE, USER_AGENT,
//     },
//     redirect::Policy,
//     Error as ReqwestError,
// };
use super::RepoInfo;
use std::num::ParseIntError;
use std::path::{Component, Path, PathBuf};
use thiserror::Error;
use ureq::{Agent, Request};

/// Current version (used in user-agent)
const VERSION: &str = env!("CARGO_PKG_VERSION");
/// Current name (used in user-agent)
const NAME: &str = env!("CARGO_PKG_NAME");

const RANGE: &str = "Range";
const CONTENT_RANGE: &str = "Content-Range";
const LOCATION: &str = "Location";
const USER_AGENT: &str = "User-Agent";
const AUTHORIZATION: &str = "Authorization";
type HeaderMap = HashMap<&'static str, String>;
type HeaderName = &'static str;

/// Simple wrapper over [`ureq::Agent`] to include default headers
#[derive(Clone)]
pub struct HeaderAgent {
    agent: Agent,
    headers: HeaderMap,
}

impl HeaderAgent {
    fn new(agent: Agent, headers: HeaderMap) -> Self {
        Self { agent, headers }
    }

    fn get(&self, url: &str) -> ureq::Request {
        let mut request = self.agent.get(url);
        for (header, value) in &self.headers {
            request = request.set(header, value);
        }
        request
    }
}

#[derive(Debug, Error)]
/// All errors the API can throw
pub enum ApiError {
    /// Api expects certain header to be present in the results to derive some information
    #[error("Header {0} is missing")]
    MissingHeader(HeaderName),

    /// The header exists, but the value is not conform to what the Api expects.
    #[error("Header {0} is invalid")]
    InvalidHeader(HeaderName),

    // /// The value cannot be used as a header during request header construction
    // #[error("Invalid header value {0}")]
    // InvalidHeaderValue(#[from] InvalidHeaderValue),

    // /// The header value is not valid utf-8
    // #[error("header value is not a string")]
    // ToStr(#[from] ToStrError),
    /// Error in the request
    #[error("request error: {0}")]
    RequestError(#[from] Box<ureq::Error>),

    /// Error parsing some range value
    #[error("Cannot parse int")]
    ParseIntError(#[from] ParseIntError),

    /// I/O Error
    #[error("I/O error {0}")]
    IoError(#[from] std::io::Error),

    /// We tried to download chunk too many times
    #[error("Too many retries: {0}")]
    TooManyRetries(Box<ApiError>),
}

/// Helper to create [`Api`] with all the options.
pub struct ApiBuilder {
    endpoint: String,
    cache: Cache,
    url_template: String,
    token: Option<String>,
    progress: bool,
}

impl Default for ApiBuilder {
    fn default() -> Self {
        Self::new()
    }
}

impl ApiBuilder {
    /// Default api builder
    /// ```
    /// use hf_hub::api::sync::ApiBuilder;
    /// let api = ApiBuilder::new().build().unwrap();
    /// ```
    pub fn new() -> Self {
        let cache = Cache::default();
        Self::from_cache(cache)
    }

    /// From a given cache
    /// ```
    /// use hf_hub::{api::sync::ApiBuilder, Cache};
    /// let path = std::path::PathBuf::from("/tmp");
    /// let cache = Cache::new(path);
    /// let api = ApiBuilder::from_cache(cache).build().unwrap();
    /// ```
    pub fn from_cache(cache: Cache) -> Self {
        let token = cache.token();

        let progress = true;

        Self {
            endpoint: "https://huggingface.co".to_string(),
            url_template: "{endpoint}/{repo_id}/resolve/{revision}/{filename}".to_string(),
            cache,
            token,
            progress,
        }
    }

    /// Wether to show a progressbar
    pub fn with_progress(mut self, progress: bool) -> Self {
        self.progress = progress;
        self
    }

    /// Changes the location of the cache directory. Defaults is `~/.cache/huggingface/`.
    pub fn with_cache_dir(mut self, cache_dir: PathBuf) -> Self {
        self.cache = Cache::new(cache_dir);
        self
    }

    /// Sets the token to be used in the API
    pub fn with_token(mut self, token: Option<String>) -> Self {
        self.token = token;
        self
    }

    fn build_headers(&self) -> Result<HeaderMap, ApiError> {
        let mut headers = HeaderMap::new();
        let user_agent = format!("unkown/None; {NAME}/{VERSION}; rust/unknown");
        headers.insert(USER_AGENT, user_agent);
        if let Some(token) = &self.token {
            headers.insert(AUTHORIZATION, format!("Bearer {token}"));
        }
        Ok(headers)
    }

    /// Consumes the builder and buids the final [`Api`]
    pub fn build(self) -> Result<Api, ApiError> {
        let headers = self.build_headers()?;
        let client = HeaderAgent::new(ureq::builder().build(), headers.clone());
        let no_redirect_client = HeaderAgent::new(ureq::builder().redirects(0).build(), headers);
        Ok(Api {
            endpoint: self.endpoint,
            url_template: self.url_template,
            cache: self.cache,
            client,

            no_redirect_client,
            progress: self.progress,
        })
    }
}

#[derive(Debug)]
struct Metadata {
    commit_hash: String,
    etag: String,
    size: usize,
}

/// The actual Api used to interacto with the hub.
/// You can inspect repos with [`Api::info`]
/// or download files with [`Api::download`]
#[derive(Clone)]
pub struct Api {
    endpoint: String,
    url_template: String,
    cache: Cache,
    client: HeaderAgent,
    no_redirect_client: HeaderAgent,
    progress: bool,
}

fn make_relative(src: &Path, dst: &Path) -> PathBuf {
    let path = src;
    let base = dst;

    if path.is_absolute() != base.is_absolute() {
        panic!("This function is made to look at absolute paths only");
    }
    let mut ita = path.components();
    let mut itb = base.components();

    loop {
        match (ita.next(), itb.next()) {
            (Some(a), Some(b)) if a == b => (),
            (some_a, _) => {
                // Ignoring b, because 1 component is the filename
                // for which we don't need to go back up for relative
                // filename to work.
                let mut new_path = PathBuf::new();
                for _ in itb {
                    new_path.push(Component::ParentDir);
                }
                if let Some(a) = some_a {
                    new_path.push(a);
                    for comp in ita {
                        new_path.push(comp);
                    }
                }
                return new_path;
            }
        }
    }
}

fn symlink_or_rename(src: &Path, dst: &Path) -> Result<(), std::io::Error> {
    if dst.exists() {
        return Ok(());
    }

    let rel_src = make_relative(src, dst);
    #[cfg(target_os = "windows")]
    {
        if std::os::windows::fs::symlink_file(rel_src, dst).is_err() {
            std::fs::rename(src, dst)?;
        }
    }

    #[cfg(target_family = "unix")]
    std::os::unix::fs::symlink(rel_src, dst)?;

    Ok(())
}

impl Api {
    /// Creates a default Api, for Api options See [`ApiBuilder`]
    pub fn new() -> Result<Self, ApiError> {
        ApiBuilder::new().build()
    }

    /// Get the underlying api client
    /// Allows for lower level access
    pub fn client(&self) -> &HeaderAgent {
        &self.client
    }

    fn metadata(&self, url: &str) -> Result<Metadata, ApiError> {
        let response = self
            .no_redirect_client
            .get(url)
            .set(RANGE, "bytes=0-0")
            .call()
            .map_err(Box::new)?;
        // let headers = response.headers();
        let header_commit = "x-repo-commit";
        let header_linked_etag = "x-linked-etag";
        let header_etag = "etag";

        let etag = match response.header(header_linked_etag) {
            Some(etag) => etag,
            None => response
                .header(header_etag)
                .ok_or(ApiError::MissingHeader(header_etag))?,
        };
        // Cleaning extra quotes
        let etag = etag.to_string().replace('"', "");
        let commit_hash = response
            .header(header_commit)
            .ok_or(ApiError::MissingHeader(header_commit))?
            .to_string();

        // The response was redirected o S3 most likely which will
        // know about the size of the file
        let status = response.status();
        let is_redirection = (300..400).contains(&status);
        let response = if is_redirection {
            self.client
                .get(response.header(LOCATION).unwrap())
                .set(RANGE, "bytes=0-0")
                .call()
                .map_err(Box::new)?
        } else {
            response
        };
        let content_range = response
            .header(CONTENT_RANGE)
            .ok_or(ApiError::MissingHeader(CONTENT_RANGE))?;

        let size = content_range
            .split('/')
            .last()
            .ok_or(ApiError::InvalidHeader(CONTENT_RANGE))?
            .parse()?;
        Ok(Metadata {
            commit_hash,
            etag,
            size,
        })
    }

    fn download_tempfile(
        &self,
        url: &str,
        progressbar: Option<ProgressBar>,
    ) -> Result<PathBuf, ApiError> {
        let filename = self.cache.temp_path();

        // Create the file and set everything properly
        let mut file = std::fs::File::create(&filename)?;

        let response = self.client.get(url).call().map_err(Box::new)?;

        let mut reader = response.into_reader();
        if let Some(p) = &progressbar {
            reader = Box::new(p.wrap_read(reader));
        }

        std::io::copy(&mut reader, &mut file)?;

        if let Some(p) = progressbar {
            p.finish()
        }
        Ok(filename)
    }

    /// Creates a new handle [`ApiRepo`] which contains operations
    /// on a particular [`Repo`]
    pub fn repo(&self, repo: Repo) -> ApiRepo {
        ApiRepo::new(self.clone(), repo)
    }

    /// Simple wrapper over
    /// ```
    /// # use hf_hub::{api::sync::Api, Repo, RepoType};
    /// # let model_id = "gpt2".to_string();
    /// let api = Api::new().unwrap();
    /// let api = api.repo(Repo::new(model_id, RepoType::Model));
    /// ```
    pub fn model(&self, model_id: String) -> ApiRepo {
        self.repo(Repo::new(model_id, RepoType::Model))
    }

    /// Simple wrapper over
    /// ```
    /// # use hf_hub::{api::sync::Api, Repo, RepoType};
    /// # let model_id = "gpt2".to_string();
    /// let api = Api::new().unwrap();
    /// let api = api.repo(Repo::new(model_id, RepoType::Dataset));
    /// ```
    pub fn dataset(&self, model_id: String) -> ApiRepo {
        self.repo(Repo::new(model_id, RepoType::Dataset))
    }

    /// Simple wrapper over
    /// ```
    /// # use hf_hub::{api::sync::Api, Repo, RepoType};
    /// # let model_id = "gpt2".to_string();
    /// let api = Api::new().unwrap();
    /// let api = api.repo(Repo::new(model_id, RepoType::Space));
    /// ```
    pub fn space(&self, model_id: String) -> ApiRepo {
        self.repo(Repo::new(model_id, RepoType::Space))
    }
}

/// Shorthand for accessing things within a particular repo
pub struct ApiRepo {
    api: Api,
    repo: Repo,
}

impl ApiRepo {
    fn new(api: Api, repo: Repo) -> Self {
        Self { api, repo }
    }
}

impl ApiRepo {
    /// Get the fully qualified URL of the remote filename
    /// ```
    /// # use hf_hub::api::sync::Api;
    /// let api = Api::new().unwrap();
    /// let url = api.model("gpt2".to_string()).url("model.safetensors");
    /// assert_eq!(url, "https://huggingface.co/gpt2/resolve/main/model.safetensors");
    /// ```
    pub fn url(&self, filename: &str) -> String {
        let endpoint = &self.api.endpoint;
        let revision = &self.repo.url_revision();
        self.api
            .url_template
            .replace("{endpoint}", endpoint)
            .replace("{repo_id}", &self.repo.url())
            .replace("{revision}", revision)
            .replace("{filename}", filename)
    }

    /// This will attempt the fetch the file locally first, then [`Api.download`]
    /// if the file is not present.
    /// ```no_run
    /// use hf_hub::{api::sync::Api};
    /// let api = Api::new().unwrap();
    /// let local_filename = api.model("gpt2".to_string()).get("model.safetensors").unwrap();
    pub fn get(&self, filename: &str) -> Result<PathBuf, ApiError> {
        if let Some(path) = self.api.cache.repo(self.repo.clone()).get(filename) {
            Ok(path)
        } else {
            self.download(filename)
        }
    }

    /// Downloads a remote file (if not already present) into the cache directory
    /// to be used locally.
    /// This functions require internet access to verify if new versions of the file
    /// exist, even if a file is already on disk at location.
    /// ```no_run
    /// # use hf_hub::api::sync::Api;
    /// let api = Api::new().unwrap();
    /// let local_filename = api.model("gpt2".to_string()).download("model.safetensors").unwrap();
    /// ```
    pub fn download(&self, filename: &str) -> Result<PathBuf, ApiError> {
        let url = self.url(filename);
        let metadata = self.api.metadata(&url)?;

        let blob_path = self
            .api
            .cache
            .repo(self.repo.clone())
            .blob_path(&metadata.etag);
        std::fs::create_dir_all(blob_path.parent().unwrap())?;

        let progressbar = if self.api.progress {
            let progress = ProgressBar::new(metadata.size as u64);
            progress.set_style(
                ProgressStyle::with_template(
                    "{msg} [{elapsed_precise}] [{wide_bar}] {bytes}/{total_bytes} {bytes_per_sec} ({eta})",
                )
                .unwrap(), // .progress_chars("━ "),
            );
            let maxlength = 30;
            let message = if filename.len() > maxlength {
                format!("..{}", &filename[filename.len() - maxlength..])
            } else {
                filename.to_string()
            };
            progress.set_message(message);
            Some(progress)
        } else {
            None
        };

        let tmp_filename = self.api.download_tempfile(&url, progressbar)?;

        std::fs::rename(tmp_filename, &blob_path)?;

        let mut pointer_path = self
            .api
            .cache
            .repo(self.repo.clone())
            .pointer_path(&metadata.commit_hash);
        pointer_path.push(filename);
        std::fs::create_dir_all(pointer_path.parent().unwrap()).ok();

        symlink_or_rename(&blob_path, &pointer_path)?;
        self.api
            .cache
            .repo(self.repo.clone())
            .create_ref(&metadata.commit_hash)?;

        Ok(pointer_path)
    }

    /// Get information about the Repo
    /// ```
    /// use hf_hub::{api::sync::Api};
    /// let api = Api::new().unwrap();
    /// api.model("gpt2".to_string()).info();
    /// ```
    pub fn info(&self) -> Result<RepoInfo, ApiError> {
        Ok(self.info_request().call().map_err(Box::new)?.into_json()?)
    }

    /// Get the raw [`ureq::Request`] with the url and method already set
    /// ```
    /// # use hf_hub::api::sync::Api;
    /// let api = Api::new().unwrap();
    /// api.model("gpt2".to_owned())
    ///     .info_request()
    ///     .query("blobs", "true")
    ///     .call();
    /// ```
    pub fn info_request(&self) -> Request {
        let url = format!("{}/api/{}", self.api.endpoint, self.repo.api_url());
        self.api.client.get(&url)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::api::Siblings;
    use crate::RepoType;
    use hex_literal::hex;
    use rand::{distributions::Alphanumeric, Rng};
    use serde_json::{json, Value};
    use sha2::{Digest, Sha256};

    struct TempDir {
        path: PathBuf,
    }

    impl TempDir {
        pub fn new() -> Self {
            let s: String = rand::thread_rng()
                .sample_iter(&Alphanumeric)
                .take(7)
                .map(char::from)
                .collect();
            let mut path = std::env::temp_dir();
            path.push(s);
            std::fs::create_dir(&path).unwrap();
            Self { path }
        }
    }

    impl Drop for TempDir {
        fn drop(&mut self) {
            std::fs::remove_dir_all(&self.path).unwrap()
        }
    }

    #[test]
    fn simple() {
        let tmp = TempDir::new();
        let api = ApiBuilder::new()
            .with_progress(false)
            .with_cache_dir(tmp.path.clone())
            .build()
            .unwrap();

        let model_id = "julien-c/dummy-unknown".to_string();
        let downloaded_path = api.model(model_id.clone()).download("config.json").unwrap();
        assert!(downloaded_path.exists());
        let val = Sha256::digest(std::fs::read(&*downloaded_path).unwrap());
        assert_eq!(
            val[..],
            hex!("b908f2b7227d4d31a2105dfa31095e28d304f9bc938bfaaa57ee2cacf1f62d32")
        );

        // Make sure the file is now seeable without connection
        let cache_path = api
            .cache
            .repo(Repo::new(model_id, RepoType::Model))
            .get("config.json")
            .unwrap();
        assert_eq!(cache_path, downloaded_path);
    }

    #[test]
    fn dataset() {
        let tmp = TempDir::new();
        let api = ApiBuilder::new()
            .with_progress(false)
            .with_cache_dir(tmp.path.clone())
            .build()
            .unwrap();
        let repo = Repo::with_revision(
            "wikitext".to_string(),
            RepoType::Dataset,
            "refs/convert/parquet".to_string(),
        );
        let downloaded_path = api
            .repo(repo)
            .download("wikitext-103-v1/test/0000.parquet")
            .unwrap();
        assert!(downloaded_path.exists());
        let val = Sha256::digest(std::fs::read(&*downloaded_path).unwrap());
        assert_eq!(
            val[..],
            hex!("59ce09415ad8aa45a9e34f88cec2548aeb9de9a73fcda9f6b33a86a065f32b90")
        )
    }

    #[test]
    fn info() {
        let tmp = TempDir::new();
        let api = ApiBuilder::new()
            .with_progress(false)
            .with_cache_dir(tmp.path.clone())
            .build()
            .unwrap();
        let repo = Repo::with_revision(
            "wikitext".to_string(),
            RepoType::Dataset,
            "refs/convert/parquet".to_string(),
        );
        let model_info = api.repo(repo).info().unwrap();
        assert_eq!(
            model_info,
            RepoInfo {
                siblings: vec![
                    Siblings {
                        rfilename: ".gitattributes".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-raw-v1/test/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-raw-v1/test/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-raw-v1/train/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-raw-v1/train/0001.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-raw-v1/train/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-raw-v1/validation/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-raw-v1/validation/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-v1/test/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-v1/test/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-v1/train/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-v1/train/0001.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-v1/train/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-v1/validation/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-103-v1/validation/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-raw-v1/test/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-raw-v1/test/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-raw-v1/train/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-raw-v1/train/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-raw-v1/validation/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-raw-v1/validation/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-v1/test/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-v1/test/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-v1/train/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-v1/train/index.duckdb".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-v1/validation/0000.parquet".to_string()
                    },
                    Siblings {
                        rfilename: "wikitext-2-v1/validation/index.duckdb".to_string()
                    }
                ],
                sha: "f23dc6c07c427c9908f56bdb9829b0a767578ee5".to_string()
            }
        )
    }

    #[test]
    fn detailed_info() {
        let tmp = TempDir::new();
        let api = ApiBuilder::new()
            .with_progress(false)
            .with_token(None)
            .with_cache_dir(tmp.path.clone())
            .build()
            .unwrap();
        let repo = Repo::with_revision(
            "mcpotato/42-eicar-street".to_string(),
            RepoType::Model,
            "8b3861f6931c4026b0cd22b38dbc09e7668983ac".to_string(),
        );
        let blobs_info: Value = api
            .repo(repo)
            .info_request()
            .query("blobs", "true")
            .call()
            .unwrap()
            .into_json()
            .unwrap();
        assert_eq!(
            blobs_info,
            json!({
                "_id": "621ffdc136468d709f17ddb4",
                "author": "mcpotato",
                "config": {},
                "disabled": false,
                "downloads": 0,
                "gated": false,
                "id": "mcpotato/42-eicar-street",
                "lastModified": "2022-11-30T19:54:16.000Z",
                "likes": 0,
                "modelId": "mcpotato/42-eicar-street",
                "private": false,
                "sha": "8b3861f6931c4026b0cd22b38dbc09e7668983ac",
                "siblings": [
                    {
                        "blobId": "6d34772f5ca361021038b404fb913ec8dc0b1a5a",
                        "rfilename": ".gitattributes",
                        "size": 1175
                    },
                    {
                        "blobId": "be98037f7c542112c15a1d2fc7e2a2427e42cb50",
                        "rfilename": "build_pickles.py",
                        "size": 304
                    },
                    {
                        "blobId": "8acd02161fff53f9df9597e377e22b04bc34feff",
                        "rfilename": "danger.dat",
                        "size": 66
                    },
                    {
                        "blobId": "86b812515e075a1ae216e1239e615a1d9e0b316e",
                        "rfilename": "eicar_test_file",
                        "size": 70
                    },
                    {
                        "blobId": "86b812515e075a1ae216e1239e615a1d9e0b316e",
                        "rfilename": "eicar_test_file_bis",
                        "size":70
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