//! HTTP client.
//!
//! dle.rae.es answers 403 to short or missing user agents, so requests to it
//! identify as a desktop browser.

use std::time::Duration;

use anyhow::{Context, Result};
use ureq::Agent;

/// Browser user agent, for dle.rae.es, which rejects clients that do not
/// identify as one.
pub const BROWSER_UA: &str = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 \
                              (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36";

/// Honest identification for APIs that want to know who is calling, as the
/// Wikimedia policy asks.
pub const CLIENT_UA: &str = concat!(
    "drae-cli/",
    env!("CARGO_PKG_VERSION"),
    " (terminal dictionary)"
);

pub struct Http {
    agent: Agent,
}

impl Http {
    pub fn new(timeout_secs: u64) -> Self {
        let config = Agent::config_builder()
            .timeout_global(Some(Duration::from_secs(timeout_secs)))
            // A 404 is an answer we want to read, not a network error.
            .http_status_as_error(false)
            .build();
        Http {
            agent: config.new_agent(),
        }
    }

    /// Returns the status code and the body.
    pub fn get(&self, url: &str, user_agent: &str) -> Result<(u16, String)> {
        let mut res = self
            .agent
            .get(url)
            .header("User-Agent", user_agent)
            .header("Accept-Language", "es-ES,es;q=0.9")
            .header("Accept", "text/html,application/json;q=0.9,*/*;q=0.8")
            .call()
            .with_context(|| format!("no se pudo conectar con {url}"))?;
        let status = res.status().as_u16();
        let body = res
            .body_mut()
            .read_to_string()
            .with_context(|| format!("respuesta ilegible de {url}"))?;
        Ok((status, body))
    }
}

/// Encodes a word for a URL path. The RAE needs `%C3%B1` for ñ; other safe
/// characters pass through unchanged.
pub fn percent_encode(s: &str) -> String {
    let mut out = String::with_capacity(s.len());
    for b in s.as_bytes() {
        match b {
            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
                out.push(*b as char)
            }
            _ => out.push_str(&format!("%{b:02X}")),
        }
    }
    out
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn encodes_spanish_characters() {
        assert_eq!(percent_encode("año"), "a%C3%B1o");
        assert_eq!(percent_encode("café"), "caf%C3%A9");
        assert_eq!(percent_encode("perro"), "perro");
        assert_eq!(percent_encode("dar de sí"), "dar%20de%20s%C3%AD");
    }
}