bunflared 0.9.0

//! A screenshot in a tool's answer, as an image the agent sees and not only
//! as a path it would have to open.

use std::path::Path;

use serde_json::{Value, json};

const ALPHABET: &[u8; 64] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

pub fn block(path: &Path) -> Option<Value> {
    let mime = match path.extension()?.to_str()? {
        "png" => "image/png",
        "jpg" => "image/jpeg",
        "webp" => "image/webp",
        _ => return None,
    };
    let bytes = std::fs::read(path).ok()?;
    Some(json!({ "type": "image", "data": base64(&bytes), "mimeType": mime }))
}

fn base64(bytes: &[u8]) -> String {
    let mut out = String::with_capacity(bytes.len().div_ceil(3) * 4);
    for chunk in bytes.chunks(3) {
        let n = chunk
            .iter()
            .enumerate()
            .fold(0u32, |n, (i, &byte)| n | u32::from(byte) << (16 - 8 * i));
        for i in 0..4 {
            out.push(if i <= chunk.len() {
                ALPHABET[(n >> (18 - 6 * i) & 63) as usize] as char
            } else {
                '='
            });
        }
    }
    out
}