use std::path::PathBuf;
use tempfile::Builder;

#[derive(Debug)]
pub enum PasteImageError {
    ClipboardUnavailable(String),
    NoImage(String),
    EncodeFailed(String),
    IoError(String),
}

impl std::fmt::Display for PasteImageError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            PasteImageError::ClipboardUnavailable(msg) => write!(f, "clipboard unavailable: {msg}"),
            PasteImageError::NoImage(msg) => write!(f, "no image on clipboard: {msg}"),
            PasteImageError::EncodeFailed(msg) => write!(f, "could not encode image: {msg}"),
            PasteImageError::IoError(msg) => write!(f, "io error: {msg}"),
        }
    }
}
impl std::error::Error for PasteImageError {}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum EncodedImageFormat {
    Png,
}

impl EncodedImageFormat {
    pub fn label(self) -> &'static str {
        match self {
            EncodedImageFormat::Png => "PNG",
        }
    }
}

#[derive(Debug, Clone)]
pub struct PastedImageInfo {
    pub width: u32,
    pub height: u32,
    pub encoded_format: EncodedImageFormat, // Always PNG for now.
}

/// Capture image from system clipboard, encode to PNG, and return bytes + info.
pub fn paste_image_as_png() -> Result<(Vec<u8>, PastedImageInfo), PasteImageError> {
    tracing::debug!("attempting clipboard image read");
    let mut cb = arboard::Clipboard::new()
        .map_err(|e| PasteImageError::ClipboardUnavailable(e.to_string()))?;
    let img = cb
        .get_image()
        .map_err(|e| PasteImageError::NoImage(e.to_string()))?;
    let w = img.width as u32;
    let h = img.height as u32;

    let mut png: Vec<u8> = Vec::new();
    let Some(rgba_img) = image::RgbaImage::from_raw(w, h, img.bytes.into_owned()) else {
        return Err(PasteImageError::EncodeFailed("invalid RGBA buffer".into()));
    };
    let dyn_img = image::DynamicImage::ImageRgba8(rgba_img);
    tracing::debug!("clipboard image decoded RGBA {w}x{h}");
    {
        let mut cursor = std::io::Cursor::new(&mut png);
        dyn_img
            .write_to(&mut cursor, image::ImageFormat::Png)
            .map_err(|e| PasteImageError::EncodeFailed(e.to_string()))?;
    }

    tracing::debug!(
        "clipboard image encoded to PNG ({len} bytes)",
        len = png.len()
    );
    Ok((
        png,
        PastedImageInfo {
            width: w,
            height: h,
            encoded_format: EncodedImageFormat::Png,
        },
    ))
}

/// Convenience: write to a temp file and return its path + info.
pub fn paste_image_to_temp_png() -> Result<(PathBuf, PastedImageInfo), PasteImageError> {
    let (png, info) = paste_image_as_png()?;
    // Create a unique temporary file with a .png suffix to avoid collisions.
    let tmp = Builder::new()
        .prefix("codex-clipboard-")
        .suffix(".png")
        .tempfile()
        .map_err(|e| PasteImageError::IoError(e.to_string()))?;
    std::fs::write(tmp.path(), &png).map_err(|e| PasteImageError::IoError(e.to_string()))?;
    // Persist the file (so it remains after the handle is dropped) and return its PathBuf.
    let (_file, path) = tmp
        .keep()
        .map_err(|e| PasteImageError::IoError(e.error.to_string()))?;
    Ok((path, info))
}