refimage 0.13.1

use std::{
    collections::HashMap,
    time::{Duration, SystemTime},
};

use serde::Serialize;

use crate::{
    genericimageowned::GenericImageOwned,
    metadata::{name_check, InsertValue},
    BayerError, CalcOptExp, Debayer, DemosaicMethod, DynamicImageRef, GenericLineItem, ImageProps,
    OptimumExposure, EXPOSURE_KEY, TIMESTAMP_KEY,
};

#[allow(unused_imports)]
use crate::ColorSpace;

/// A serializable, generic image with metadata, backed by [`DynamicImageRef`].
///
/// This struct holds an image with associated metadata. The metadata is stored as a vector of
/// [`GenericLineItem`] structs. The image data is stored as a [`DynamicImageRef`].
///
/// # Note
/// - Internally [`GenericImageRef`] and [`GenericImageOwned`] serialize to the same
///   representation, and can be deserialized into each other.
///
/// # Usage
/// ```
/// use refimage::{ImageRef, DynamicImageRef, GenericImageRef, ColorSpace};
/// use std::time::SystemTime;
/// let mut data = vec![1u8, 2, 3, 4, 5, 6];
/// let img = ImageRef::new(&mut data, 3, 2, ColorSpace::Gray).unwrap();
/// let img = DynamicImageRef::from(img);
/// let mut img = GenericImageRef::new(std::time::SystemTime::now(), img);
///
/// img.insert_key("CAMERA", "Canon EOS 5D Mark IV").unwrap();
/// ```
#[derive(Debug, PartialEq, Serialize)]
pub struct GenericImageRef<'a> {
    pub(crate) metadata: HashMap<String, GenericLineItem>,
    #[serde(borrow)]
    pub(crate) image: DynamicImageRef<'a>,
}

impl<'a> GenericImageRef<'a> {
    /// Create a new [`GenericImageRef`] with metadata.
    ///
    /// # Arguments
    /// - `tstamp`: The timestamp of the image.
    /// - `image`: The image data, of type [`DynamicImageRef`].
    ///
    /// # Example
    /// ```
    /// use refimage::{ImageRef, DynamicImageRef, GenericImageRef, ColorSpace};
    /// use std::time::SystemTime;
    /// let mut data = vec![1u8, 2, 3, 4, 5, 6];
    /// let img = ImageRef::new(&mut data, 3, 2, ColorSpace::Gray).unwrap();
    /// let img = DynamicImageRef::from(img);
    /// let mut img = GenericImageRef::new(std::time::SystemTime::now(), img);
    ///
    /// img.insert_key("CAMERA", "Canon EOS 5D Mark IV").unwrap();
    /// ```
    pub fn new(tstamp: SystemTime, image: DynamicImageRef<'a>) -> Self {
        let mut metadata = HashMap::new();
        metadata.insert(
            TIMESTAMP_KEY.to_string(),
            GenericLineItem {
                value: tstamp.into(),
                comment: Some("Timestamp of the image".to_owned()),
            },
        );
        Self { metadata, image }
    }

    /// Get the timestamp of the image.
    pub fn get_timestamp(&self) -> SystemTime {
        self.metadata
            .get(TIMESTAMP_KEY)
            .and_then(|x| x.get_value().clone().try_into().ok())
            .unwrap() // Safe to unwrap, as the timestamp key is always inserted
    }

    /// Get the exposure time of the image.
    pub fn get_exposure(&self) -> Option<Duration> {
        self.metadata
            .get(EXPOSURE_KEY)
            .and_then(|x| x.get_value().clone().try_into().ok())
    }

    /// Insert a metadata value into the [`GenericImageRef`].
    ///
    /// # Arguments
    /// - `name`: The name of the metadata value. The name must be non-empty and less than 80 characters.
    /// - `value`: The value to insert. The value is either a primitive type, a `String`, or a `std::time::Duration` or `std::time::SystemTime` or a tuple of a primitive type and a comment ().
    /// # Valid Types
    /// The valid types for the metadata value are:
    /// - [`u8`] | [`u16`] | [`u32`] | [`u64`]
    /// - [`i8`] | [`i16`] | [`i32`] | [`i64`]
    /// - [`f32`] | [`f64`]
    /// - [`ColorSpace`]
    /// - [`std::time::Duration`] | [`std::time::SystemTime`]
    /// - [`String`] | [`&str`]
    ///
    /// # Note
    /// - The metadata key is case-insensitive and is stored as an uppercase string.
    /// - Re-inserting a timestamp key will return an error.
    /// - When saving to a FITS file, the metadata comment may be truncated.
    /// - Metadata of type [`std::time::Duration`] or [`std::time::SystemTime`] is split
    ///   and stored as two consecutive metadata items, with the same key, split into
    ///   seconds ([`u64`]) and nanoseconds ([`u64`]).
    pub fn insert_key<T: InsertValue>(&mut self, name: &str, value: T) -> Result<(), &'static str> {
        if name.to_uppercase() == TIMESTAMP_KEY {
            return Err("Cannot re-insert timestamp key");
        }
        T::insert_key_gi(self, name, value)
    }

    /// Remove a metadata value from the [`GenericImageRef`].
    ///
    /// # Arguments
    /// - `name`: The name of the metadata value to remove.
    ///
    /// # Returns
    /// - `Ok(())` if the key was removed successfully.
    /// - `Err("Can not remove timestamp key")` if the key is the timestamp key.
    /// - `Err("Key not found")` if the key was not found.
    /// - `Err("Key cannot be empty")` if the key is an empty string.
    /// - `Err("Key cannot be longer than 80 characters")` if the key is longer than 80 characters.
    pub fn remove_key(&mut self, name: &str) -> Result<(), &'static str> {
        if name.to_uppercase() == TIMESTAMP_KEY {
            return Err("Cannot remove timestamp key");
        }
        name_check(name)?;
        self.metadata.remove(name).ok_or("Key not found")?;
        Ok(())
    }

    /// Replace a metadata value in the [`GenericImageRef`].
    ///
    /// # Arguments
    /// - `name`: The name of the metadata value to replace.
    /// - `value`: The new value to insert. The value is either a primitive type, a `String`, or a `std::time::Duration` or `std::time::SystemTime` or a tuple of a value type and a comment.
    ///
    /// # Returns
    /// - `Ok(())` if the key was replaced successfully.
    /// - `Err("Key not found")` if the key was not found.
    ///
    pub fn replace_key<T: InsertValue>(
        &mut self,
        name: &str,
        value: T,
    ) -> Result<(), &'static str> {
        T::replace_gi(self, name, value)
    }

    /// Get the underlying [`DynamicImageRef`].
    ///
    /// # Returns
    /// The underlying [`DynamicImageRef`] of the [`GenericImageRef`].
    pub fn get_image(&self) -> &DynamicImageRef<'a> {
        &self.image
    }

    /// Get the underlying [`DynamicImageRef`] mutably.
    pub fn get_image_mut(&mut self) -> &mut DynamicImageRef<'a> {
        &mut self.image
    }

    /// Get the contained metadata as a slice of [`GenericLineItem`]s.
    ///
    /// # Returns
    /// A slice of [`GenericLineItem`]s containing the metadata.
    pub fn get_metadata(&self) -> &HashMap<String, GenericLineItem> {
        &self.metadata
    }

    /// Get a specific metadata value by name.
    ///
    /// Returns the first metadata value with the given name.
    ///
    /// # Arguments
    /// - `name`: The name of the metadata value.
    pub fn get_key(&self, name: &str) -> Option<&GenericLineItem> {
        name_check(name).ok()?;
        self.metadata.get(name)
    }

    /// Convert the image to a [`GenericImageOwned`] with [`u8`] pixel type.
    ///
    /// Note: This operation is parallelized if the `rayon` feature is enabled.
    pub fn into_u8(self) -> GenericImageOwned {
        let img = self.image.into_u8();
        GenericImageOwned {
            metadata: self.metadata,
            image: img,
        }
    }
}

impl Debayer for GenericImageRef<'_> {
    type Output = GenericImageOwned;
    fn debayer(&self, method: DemosaicMethod) -> Result<Self::Output, BayerError> {
        let img = self.image.debayer(method)?;
        let meta = self.metadata.clone();
        Ok(Self::Output {
            metadata: meta,
            image: img,
        })
    }
}

impl CalcOptExp for GenericImageRef<'_> {
    fn calc_opt_exp(
        mut self,
        eval: &OptimumExposure,
        exposure: Duration,
        bin: u8,
    ) -> Result<(Duration, u16), &'static str> {
        match &mut self.image {
            DynamicImageRef::U8(img) => {let len = img.len(); eval.calculate(img.as_mut_slice(), len, exposure, bin)},
            DynamicImageRef::U16(img) => {let len = img.len(); eval.calculate(img.as_mut_slice(), len, exposure, bin)},
            DynamicImageRef::F32(_) => Err("Floating point images are not supported for this operation, since Ord is not implemented for floating point types."),
        }
    }
}

impl ImageProps for GenericImageRef<'_> {
    type OutputU8 = GenericImageOwned;

    fn width(&self) -> usize {
        self.image.width()
    }

    fn height(&self) -> usize {
        self.image.height()
    }

    fn channels(&self) -> u8 {
        self.image.channels()
    }

    fn color_space(&self) -> crate::ColorSpace {
        self.image.color_space()
    }

    fn pixel_type(&self) -> crate::PixelType {
        self.image.pixel_type()
    }

    fn len(&self) -> usize {
        self.image.len()
    }

    fn is_empty(&self) -> bool {
        self.image.is_empty()
    }

    fn cast_u8(&self) -> Self::OutputU8 {
        Self::OutputU8 {
            metadata: self.metadata.clone(),
            image: self.image.into_u8(),
        }
    }
}

impl GenericImageRef<'_> {
    /// Get the data as a slice of `u8`, regardless of the underlying type.
    pub fn as_raw_u8(&self) -> &[u8] {
        self.image.as_raw_u8()
    }

    /// Get the data as a slice of `u8`, regardless of the underlying type.
    pub fn as_raw_u8_checked(&self) -> Option<&[u8]> {
        self.image.as_raw_u8_checked()
    }

    /// Get the data as a slice of `u8`.
    ///
    /// # Note
    /// The returned slice is not guaranteed to have the correct length.
    /// Use [`GenericImageRef::len`] to get the correct length.
    pub fn as_slice_u8(&self) -> Option<&[u8]> {
        self.image.as_slice_u8()
    }

    /// Get the data as a mutable slice of `u8`.
    ///
    /// # Note
    /// The returned slice is not guaranteed to have the correct length.
    /// Use [`GenericImageRef::len`] to get the correct length.
    pub fn as_mut_slice_u8(&mut self) -> Option<&mut [u8]> {
        self.image.as_mut_slice_u8()
    }

    /// Get the data as a slice of `u16`.
    ///
    /// # Note
    /// The returned slice is not guaranteed to have the correct length.
    /// Use [`GenericImageRef::len`] to get the correct length.
    pub fn as_slice_u16(&self) -> Option<&[u16]> {
        self.image.as_slice_u16()
    }

    /// Get the data as a mutable slice of `u16`.
    ///
    /// # Note
    /// The returned slice is not guaranteed to have the correct length.
    /// Use [`GenericImageRef::len`] to get the correct length.
    pub fn as_mut_slice_u16(&mut self) -> Option<&mut [u16]> {
        self.image.as_mut_slice_u16()
    }

    /// Get the data as a slice of `f32`.
    ///
    /// # Note
    /// The returned slice is not guaranteed to have the correct length.
    /// Use [`GenericImageRef::len`] to get the correct length.
    pub fn as_slice_f32(&self) -> Option<&[f32]> {
        self.image.as_slice_f32()
    }

    /// Get the data as a mutable slice of `f32`.
    ///
    /// # Note
    /// The returned slice is not guaranteed to have the correct length.
    /// Use [`GenericImageRef::len`] to get the correct length.
    pub fn as_mut_slice_f32(&mut self) -> Option<&mut [f32]> {
        self.image.as_mut_slice_f32()
    }
}

mod test {
    #[test]
    fn test_optimum_exposure() {
        use crate::CalcOptExp;
        let opt_exp = crate::OptimumExposureBuilder::default()
            .pixel_exclusion(1)
            .build()
            .unwrap();
        let mut img = vec![0u8, 1, 2, 3, 4, 5, 6, 7, 8, 9];
        let img = crate::ImageRef::new(img.as_mut_slice(), 5, 2, crate::ColorSpace::Gray)
            .expect("Failed to create ImageOwned");
        let img = crate::DynamicImageRef::from(img);
        let img = crate::GenericImageRef::new(std::time::SystemTime::now(), img);
        let exp = std::time::Duration::from_secs(10); // expected exposure
        let bin = 1; // expected binning
        let res = img.calc_opt_exp(&opt_exp, exp, bin).unwrap();
        assert_eq!(res, (exp, bin as u16));
    }
}