use crate::config::CONFIG_INSTANCE;
use crate::constants::{PHOTO_BASE_XY, PHOTO_FULLSIZE_XY, PHOTO_THUMBNAIL_XY};
use crate::error::DichroismError;
use crate::models::{Photo, PhotoSet};
use exif::Reader;
use image::imageops::FilterType;
use image::DynamicImage;
use image::GenericImageView;
use std::io::{BufReader, Cursor};
use std::path::PathBuf;
use uuid::Uuid;

pub fn generate_photo_set(data: Vec<u8>) -> Result<PhotoSet, DichroismError> {
    // load image data from bytes
    let mut original = image::load_from_memory(&data)?;

    // read EXIF tags to check for required rotation
    let exifreader = Reader::new();
    let mut reader = BufReader::new(Cursor::new(data));
    let exif = exifreader.read_from_container(&mut reader).unwrap();
    if let Some(orient) = exif
        .get_field(exif::Tag::Orientation, exif::In::PRIMARY)
        .map(|o| o.value.get_uint(0))
        .flatten()
    {
        // if a tag was present, rotate original image data as necessary
        match orient {
            8 => original = original.rotate270(),
            3 => original = original.rotate180(),
            6 => original = original.rotate90(),
            _ => {}
        }
    }

    let fullsize = original.resize(PHOTO_FULLSIZE_XY, PHOTO_FULLSIZE_XY, FilterType::Lanczos3);
    let base = original.resize(PHOTO_BASE_XY, PHOTO_BASE_XY, FilterType::Lanczos3);

    let (width, height) = original.dimensions();
    let thumbnail = if width > height {
        let offset = (width - height) / 2;
        original.crop_imm(offset, 0, width - offset * 2, height)
    } else {
        let offset = (height - width) / 2;
        original.crop_imm(0, offset, width, height - offset * 2)
    }
    .resize(PHOTO_THUMBNAIL_XY, PHOTO_THUMBNAIL_XY, FilterType::Lanczos3);

    Ok(PhotoSet {
        id: None,
        original: generate_photo(&original)?,
        fullsize: generate_photo(&fullsize)?,
        base: generate_photo(&base)?,
        thumbnail: generate_photo(&thumbnail)?,
    })
}

fn generate_photo(image: &DynamicImage) -> Result<Photo, DichroismError> {
    let base_name = Uuid::new_v3(&Uuid::NAMESPACE_OID, &image.to_bytes())
        .to_hyphenated()
        .to_string();
    let mut path = PathBuf::from(&CONFIG_INSTANCE.img_root);
    path.push(base_name);
    path.set_extension("jpg");
    image.save(&path)?;

    let id = path
        .file_name()
        .ok_or_else(|| {
            DichroismError::ImageWrite("Error extracting filename from path".to_string())
        })?
        .to_str()
        .ok_or_else(|| {
            DichroismError::ImageWrite("Error converting filename to slice".to_string())
        })?;
    Ok(Photo::new(String::from(id)))
}