use std::io::{BufRead, Read, Seek, Write};

use aes_gcm::{
    aead::{AeadCore, AeadMutInPlace, OsRng},
    Aes256Gcm, Key, KeyInit, Nonce,
};
use image::{DynamicImage, ImageBuffer};
use revolt_config::{config, report_internal_error, FilesS3};
use revolt_result::{create_error, Result};

use aws_sdk_s3::{
    config::{Credentials, Region},
    Client, Config,
};

use base64::prelude::*;
use tempfile::NamedTempFile;
use tiny_skia::Pixmap;

/// Size of the authentication tag in the buffer
pub const AUTHENTICATION_TAG_SIZE_BYTES: usize = 16;

/// Create an S3 client
pub fn create_client(s3_config: FilesS3) -> Client {
    let provider_name = "my-creds";
    let creds = Credentials::new(
        s3_config.access_key_id,
        s3_config.secret_access_key,
        None,
        None,
        provider_name,
    );

    let config = Config::builder()
        .region(Region::new(s3_config.region))
        .endpoint_url(s3_config.endpoint)
        .force_path_style(s3_config.path_style_buckets)
        .credentials_provider(creds)
        .build();

    Client::from_conf(config)
}

/// Create an AES-256-GCM cipher
pub fn create_cipher(key: &str) -> Aes256Gcm {
    let key = &BASE64_STANDARD.decode(key).expect("valid base64 string")[..];
    let key: &Key<Aes256Gcm> = key.into();
    Aes256Gcm::new(key)
}

/// Fetch a file from S3 (and decrypt it)
pub async fn fetch_from_s3(bucket_id: &str, path: &str, nonce: &str) -> Result<Vec<u8>> {
    let config = config().await;
    let client = create_client(config.files.s3);

    // Send a request for the file
    let mut obj =
        report_internal_error!(client.get_object().bucket(bucket_id).key(path).send().await)?;

    // Read the file from remote
    let mut buf = vec![];
    while let Some(bytes) = obj.body.next().await {
        let data = report_internal_error!(bytes)?;
        report_internal_error!(buf.write_all(&data))?;
        // is there a more efficient way to do this?
        // we just want the Vec<u8>
    }

    // File is not encrypted
    if nonce.is_empty() {
        return Ok(buf);
    }

    // Recover nonce as bytes
    let nonce = &BASE64_STANDARD.decode(nonce).unwrap()[..];
    let nonce: &Nonce<typenum::consts::U12> = nonce.into();

    // Decrypt the file
    create_cipher(&config.files.encryption_key)
        .decrypt_in_place(nonce, b"", &mut buf)
        .map_err(|_| create_error!(InternalError))?;

    // Remove the authentication tag bytes that were added during encryption
    buf.truncate(buf.len() - AUTHENTICATION_TAG_SIZE_BYTES);

    Ok(buf)
}

/// Encrypt and upload a file to S3 (returning its nonce/IV)
pub async fn upload_to_s3(bucket_id: &str, path: &str, buf: &[u8]) -> Result<String> {
    let config = config().await;
    let client = create_client(config.files.s3);

    // Generate a nonce
    let nonce = Aes256Gcm::generate_nonce(&mut OsRng);

    // Extend the buffer for in-place encryption
    let mut buf = [buf, &[0; AUTHENTICATION_TAG_SIZE_BYTES]].concat();

    // Encrypt the file in place
    create_cipher(&config.files.encryption_key)
        .encrypt_in_place(&nonce, b"", &mut buf)
        .map_err(|_| create_error!(InternalError))?;

    // Upload the file to remote
    report_internal_error!(
        client
            .put_object()
            .bucket(bucket_id)
            .key(path)
            .body(buf.into())
            .send()
            .await
    )?;

    Ok(BASE64_STANDARD.encode(nonce))
}

/// Delete a file from S3 by path
pub async fn delete_from_s3(bucket_id: &str, path: &str) -> Result<()> {
    let config = config().await;
    let client = create_client(config.files.s3);

    report_internal_error!(
        client
            .delete_object()
            .bucket(bucket_id)
            .key(path)
            .send()
            .await
    )?;

    Ok(())
}

/// Determine size of image at temp file
pub fn image_size(f: &NamedTempFile) -> Option<(usize, usize)> {
    if let Ok(size) = imagesize::size(f.path())
        .inspect_err(|err| tracing::error!("Failed to generate image size! {err:?}"))
    {
        Some((size.width, size.height))
    } else {
        None
    }
}

/// Determine size of image with buffer
pub fn image_size_vec(v: &[u8], mime: &str) -> Option<(usize, usize)> {
    match mime {
        "image/svg+xml" => {
            let tree =
                report_internal_error!(usvg::Tree::from_data(v, &Default::default())).ok()?;

            let size = tree.size();
            Some((size.width() as usize, size.height() as usize))
        }
        _ => {
            if let Ok(size) = imagesize::blob_size(v)
                .inspect_err(|err| tracing::error!("Failed to generate image size! {err:?}"))
            {
                Some((size.width, size.height))
            } else {
                None
            }
        }
    }
}

/// Determine size of video at temp file
pub fn video_size(f: &NamedTempFile) -> Option<(i64, i64)> {
    if let Ok(data) = ffprobe::ffprobe(f.path())
        .inspect_err(|err| tracing::error!("Failed to ffprobe file! {err:?}"))
    {
        // Use first valid stream
        for stream in data.streams {
            if let (Some(w), Some(h)) = (stream.width, stream.height) {
                return Some((w, h));
            }
        }

        None
    } else {
        None
    }
}

/// Decode image from reader
pub fn decode_image<R: Read + BufRead + Seek>(reader: &mut R, mime: &str) -> Result<DynamicImage> {
    match mime {
        // Read image using jxl-oxide crate
        "image/jxl" => {
            let jxl_image = report_internal_error!(jxl_oxide::JxlImage::builder().read(reader))?;
            if let Ok(frame) = jxl_image.render_frame(0) {
                match frame.color_channels().len() {
                    3 => Ok(DynamicImage::ImageRgb8(
                        DynamicImage::ImageRgb32F(
                            ImageBuffer::from_vec(
                                jxl_image.width(),
                                jxl_image.height(),
                                frame.image().buf().to_vec(),
                            )
                            .ok_or_else(|| create_error!(ImageProcessingFailed))?,
                        )
                        .to_rgb8(),
                    )),
                    4 => Ok(DynamicImage::ImageRgba8(
                        DynamicImage::ImageRgba32F(
                            ImageBuffer::from_vec(
                                jxl_image.width(),
                                jxl_image.height(),
                                frame.image().buf().to_vec(),
                            )
                            .ok_or_else(|| create_error!(ImageProcessingFailed))?,
                        )
                        .to_rgba8(),
                    )),
                    _ => Err(create_error!(ImageProcessingFailed)),
                }
            } else {
                Err(create_error!(ImageProcessingFailed))
            }
        }
        // Read image using resvg
        "image/svg+xml" => {
            // usvg doesn't support Read trait so copy to buffer
            let mut buf = Vec::new();
            report_internal_error!(reader.read_to_end(&mut buf))?;

            let tree = report_internal_error!(usvg::Tree::from_data(&buf, &Default::default()))?;
            let size = tree.size();
            let mut pixmap = Pixmap::new(size.width() as u32, size.height() as u32)
                .ok_or_else(|| create_error!(ImageProcessingFailed))?;

            let mut pixmap_mut = pixmap.as_mut();
            resvg::render(&tree, Default::default(), &mut pixmap_mut);

            Ok(DynamicImage::ImageRgba8(
                ImageBuffer::from_vec(
                    size.width() as u32,
                    size.height() as u32,
                    pixmap.data().to_vec(),
                )
                .ok_or_else(|| create_error!(ImageProcessingFailed))?,
            ))
        }
        // Check if we can read using image-rs crate
        _ => report_internal_error!(report_internal_error!(
            image::ImageReader::new(reader).with_guessed_format()
        )?
        .decode()),
    }
}

/// Check whether given reader has a valid image
pub fn is_valid_image<R: Read + BufRead + Seek>(reader: &mut R, mime: &str) -> bool {
    match mime {
        // Check if we can read using jxl-oxide crate
        "image/jxl" => jxl_oxide::JxlImage::builder()
            .read(reader)
            .inspect_err(|err| tracing::error!("Failed to read JXL! {err:?}"))
            .is_ok(),
        // Check if we can read using image-rs crate
        _ => !matches!(
            image::ImageReader::new(reader)
                .with_guessed_format()
                .inspect_err(|err| tracing::error!("Failed to read image! {err:?}"))
                .map(|f| f.decode()),
            Err(_) | Ok(Err(_))
        ),
    }
}

/// Create thumbnail from given image
pub async fn create_thumbnail(image: DynamicImage, tag: &str) -> Vec<u8> {
    // Load configuration
    let config = config().await;
    let [w, h] = config.files.preview.get(tag).unwrap();

    // Create thumbnail
    //.resize(width as u32, height as u32, image::imageops::FilterType::Gaussian)
    // resize is about 2.5x slower,
    // thumbnail doesn't have terrible quality
    // so we use thumbnail
    let image = image.thumbnail(image.width().min(*w as u32), image.height().min(*h as u32));

    // Encode it into WEBP
    let encoder = webp::Encoder::from_image(&image).expect("Could not create encoder.");
    if config.files.webp_quality != 100.0 {
        encoder.encode(config.files.webp_quality).to_vec()
    } else {
        encoder.encode_lossless().to_vec()
    }
}