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use std::fmt;

use reqwest::header::{CONTENT_LENGTH, CONTENT_RANGE, RANGE};
use reqwest::{Body, Response};
use reqwest_middleware::ClientWithMiddleware as Client;

use crate::http::{check_response_status, objects::Object, Error};

#[derive(thiserror::Error, Debug)]
pub enum ChunkError {
    #[error("invalid range: first={0} last={1}")]
    InvalidRange(u64, u64),
    #[error("total object size must not be zero")]
    ZeroTotalObjectSize,
    #[error("last byte must be less than total object size: last={0} total={1}")]
    InvalidLastBytes(u64, u64),
}

#[derive(PartialEq, Debug)]
#[allow(clippy::large_enum_variant)]
pub enum UploadStatus {
    Ok(Object),
    NotStarted,
    ResumeIncomplete(UploadedRange),
}

#[derive(PartialEq, Debug)]
pub struct UploadedRange {
    pub first_byte: u64,
    pub last_byte: u64,
}

#[derive(Clone, Debug)]
pub struct ChunkSize {
    first_byte: u64,
    last_byte: u64,
    total_object_size: Option<u64>,
}

impl fmt::Display for ChunkSize {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if self.total_object_size == Some(self.first_byte) {
            write!(f, "bytes */")?;
        } else {
            write!(f, "bytes {}-{}/", self.first_byte, self.last_byte)?;
        }

        match self.total_object_size {
            Some(total_object_size) => write!(f, "{total_object_size}"),
            None => write!(f, "*"),
        }
    }
}

impl ChunkSize {
    pub fn new(first_byte: u64, last_byte: u64, total_object_size: Option<u64>) -> ChunkSize {
        Self {
            first_byte,
            last_byte,
            total_object_size,
        }
    }

    pub fn size(&self) -> u64 {
        if self.total_object_size == Some(self.first_byte) {
            0
        } else {
            self.last_byte - self.first_byte + 1
        }
    }
}

#[derive(Clone)]
pub struct ResumableUploadClient {
    session_url: String,
    http: Client,
}

impl ResumableUploadClient {
    pub fn url(&self) -> &str {
        self.session_url.as_str()
    }

    pub fn new(session_url: String, http: Client) -> Self {
        Self { session_url, http }
    }

    /// https://cloud.google.com/storage/docs/performing-resumable-uploads#single-chunk-upload
    pub async fn upload_single_chunk<T: Into<Body>>(&self, data: T, size: usize) -> Result<(), Error> {
        let response = self
            .http
            .put(&self.session_url)
            .header(CONTENT_LENGTH, size)
            .body(data)
            .send()
            .await?;
        check_response_status(response).await?;
        Ok(())
    }

    /// https://cloud.google.com/storage/docs/performing-resumable-uploads#chunked-upload
    /// https://cloud.google.com/storage/docs/performing-resumable-uploads#resume-upload
    pub async fn upload_multiple_chunk<T: Into<Body>>(&self, data: T, size: &ChunkSize) -> Result<UploadStatus, Error> {
        let response = self
            .http
            .put(&self.session_url)
            .header(CONTENT_RANGE, size.to_string())
            .header(CONTENT_LENGTH, size.size())
            .body(data)
            .send()
            .await?;
        Self::map_resume_response(response).await
    }

    /// https://cloud.google.com/storage/docs/performing-resumable-uploads#status-check
    pub async fn status(&self, object_size: Option<u64>) -> Result<UploadStatus, Error> {
        let mut content_range = "bytes */".to_owned();
        match object_size {
            Some(object_size) => content_range.push_str(&object_size.to_string()),
            None => content_range.push('*'),
        };
        let response = self
            .http
            .put(&self.session_url)
            .header(CONTENT_RANGE, content_range)
            .header(CONTENT_LENGTH, 0)
            .body(Vec::new())
            .send()
            .await?;
        Self::map_resume_response(response).await
    }

    /// https://cloud.google.com/storage/docs/performing-resumable-uploads#cancel-upload
    pub async fn cancel(self) -> Result<(), Error> {
        let response = self
            .http
            .delete(&self.session_url)
            .header(CONTENT_LENGTH, 0)
            .send()
            .await?;
        if response.status() == 499 {
            Ok(())
        } else {
            check_response_status(response).await?;
            Ok(())
        }
    }

    async fn map_resume_response(response: Response) -> Result<UploadStatus, Error> {
        if response.status() != 308 {
            let response = check_response_status(response).await?;
            return Ok(UploadStatus::Ok(response.json::<Object>().await?));
        }

        let range = response.headers().get(RANGE);

        if range.is_none() {
            return Ok(UploadStatus::NotStarted);
        }

        let range = range
            .unwrap()
            .to_str()
            .map_err(|error| Error::InvalidRangeHeader(error.to_string()))?;

        let range = range
            .split('=')
            .nth(1)
            .ok_or_else(|| Error::InvalidRangeHeader(range.to_string()))?;

        let start_end: Vec<&str> = range.split('-').collect();
        let first_byte = start_end
            .first()
            .unwrap_or(&"0")
            .parse::<u64>()
            .map_err(|_| Error::InvalidRangeHeader(range.to_string()))?;

        let last_byte = start_end
            .get(1)
            .ok_or_else(|| Error::InvalidRangeHeader(range.to_string()))?
            .parse::<u64>()
            .map_err(|_| Error::InvalidRangeHeader(range.to_string()))?;

        Ok(UploadStatus::ResumeIncomplete(UploadedRange { first_byte, last_byte }))
    }
}