// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

use std::fmt::Debug;
use std::sync::Arc;

use http::Response;
use http::StatusCode;
use log::debug;

use super::HTTP_SCHEME;
use super::config::HttpConfig;
use super::core::HttpCore;
use super::error::parse_error;
use opendal_core::raw::*;
use opendal_core::*;

/// HTTP Read-only service support like [Nginx](https://www.nginx.com/) and [Caddy](https://caddyserver.com/).
#[doc = include_str!("docs.md")]
#[derive(Default)]
pub struct HttpBuilder {
    pub(super) config: HttpConfig,
}

impl Debug for HttpBuilder {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("HttpBuilder")
            .field("config", &self.config)
            .finish_non_exhaustive()
    }
}

impl HttpBuilder {
    /// Set endpoint for http backend.
    ///
    /// For example: `https://example.com`
    pub fn endpoint(mut self, endpoint: &str) -> Self {
        self.config.endpoint = if endpoint.is_empty() {
            None
        } else {
            Some(endpoint.to_string())
        };

        self
    }

    /// set username for http backend
    ///
    /// default: no username
    pub fn username(mut self, username: &str) -> Self {
        if !username.is_empty() {
            self.config.username = Some(username.to_owned());
        }
        self
    }

    /// set password for http backend
    ///
    /// default: no password
    pub fn password(mut self, password: &str) -> Self {
        if !password.is_empty() {
            self.config.password = Some(password.to_owned());
        }
        self
    }

    /// set bearer token for http backend
    ///
    /// default: no access token
    pub fn token(mut self, token: &str) -> Self {
        if !token.is_empty() {
            self.config.token = Some(token.to_string());
        }
        self
    }

    /// Set root path of http backend.
    pub fn root(mut self, root: &str) -> Self {
        self.config.root = if root.is_empty() {
            None
        } else {
            Some(root.to_string())
        };

        self
    }
}

impl Builder for HttpBuilder {
    type Config = HttpConfig;

    fn build(self) -> Result<impl Access> {
        debug!("backend build started: {:?}", &self);

        let endpoint = match &self.config.endpoint {
            Some(v) => v,
            None => {
                return Err(Error::new(ErrorKind::ConfigInvalid, "endpoint is empty")
                    .with_context("service", HTTP_SCHEME));
            }
        };

        let root = normalize_root(&self.config.root.unwrap_or_default());
        debug!("backend use root {root}");

        let mut auth = None;
        if let Some(username) = &self.config.username {
            auth = Some(format_authorization_by_basic(
                username,
                self.config.password.as_deref().unwrap_or_default(),
            )?);
        }
        if let Some(token) = &self.config.token {
            auth = Some(format_authorization_by_bearer(token)?)
        }

        let info = AccessorInfo::default();
        info.set_scheme(HTTP_SCHEME)
            .set_root(&root)
            .set_native_capability(Capability {
                stat: true,
                stat_with_if_match: true,
                stat_with_if_none_match: true,

                read: true,

                read_with_if_match: true,
                read_with_if_none_match: true,

                presign: auth.is_none(),
                presign_read: auth.is_none(),
                presign_stat: auth.is_none(),

                shared: true,

                ..Default::default()
            });

        let accessor_info = Arc::new(info);

        let core = Arc::new(HttpCore {
            info: accessor_info,
            endpoint: endpoint.to_string(),
            root,
            authorization: auth,
        });

        Ok(HttpBackend { core })
    }
}

/// Backend is used to serve `Accessor` support for http.
#[derive(Clone, Debug)]
pub struct HttpBackend {
    core: Arc<HttpCore>,
}

impl Access for HttpBackend {
    type Reader = HttpBody;
    type Writer = ();
    type Lister = ();
    type Deleter = ();
    type Copier = ();

    fn info(&self) -> Arc<AccessorInfo> {
        self.core.info.clone()
    }

    async fn stat(&self, path: &str, args: OpStat) -> Result<RpStat> {
        // Stat root always returns a DIR.
        if path == "/" {
            return Ok(RpStat::new(Metadata::new(EntryMode::DIR)));
        }

        let resp = self.core.http_head(path, &args).await?;

        let status = resp.status();

        match status {
            StatusCode::OK => parse_into_metadata(path, resp.headers()).map(RpStat::new),
            // HTTP Server like nginx could return FORBIDDEN if auto-index
            // is not enabled, we should ignore them.
            StatusCode::NOT_FOUND | StatusCode::FORBIDDEN if path.ends_with('/') => {
                Ok(RpStat::new(Metadata::new(EntryMode::DIR)))
            }
            _ => Err(parse_error(resp)),
        }
    }

    async fn read(&self, path: &str, args: OpRead) -> Result<(RpRead, Self::Reader)> {
        let resp = self.core.http_get(path, args.range(), &args).await?;

        let status = resp.status();

        match status {
            StatusCode::OK | StatusCode::PARTIAL_CONTENT => Ok((
                RpRead::new(parse_into_metadata(path, resp.headers())?),
                resp.into_body(),
            )),
            _ => {
                let (part, mut body) = resp.into_parts();
                let buf = body.to_buffer().await?;
                Err(parse_error(Response::from_parts(part, buf)))
            }
        }
    }

    async fn presign(&self, path: &str, args: OpPresign) -> Result<RpPresign> {
        if self.core.has_authorization() {
            return Err(Error::new(
                ErrorKind::Unsupported,
                "Http doesn't support presigned request on backend with authorization",
            ));
        }

        let req = match args.operation() {
            PresignOperation::Stat(v) => self.core.http_head_request(path, v)?,
            PresignOperation::Read(v) => {
                self.core.http_get_request(path, BytesRange::default(), v)?
            }
            _ => {
                return Err(Error::new(
                    ErrorKind::Unsupported,
                    "Http doesn't support presigned write",
                ));
            }
        };

        let (parts, _) = req.into_parts();

        Ok(RpPresign::new(PresignedRequest::new(
            parts.method,
            parts.uri,
            parts.headers,
        )))
    }
}
