use anyhow::{Context, Result};

use serde_json::Value;

/// Load a spec from a local file path or an http(s) URL.

pub async fn load_spec(source: &str) -> Result<Value> {

    if source.starts_with("http://") || source.starts_with("https://") {

        let client = reqwest::Client::new();

        let text = client

            .get(source)

            .send()

            .await

            .with_context(|| format!("fetching {source}"))?

            .error_for_status()

            .with_context(|| format!("fetching {source}"))?

            .text()

            .await

            .with_context(|| format!("reading body of {source}"))?;

        parse_spec(&text).with_context(|| format!("parsing spec from {source}"))

    } else {

        let text = std::fs::read_to_string(source).with_context(|| format!("reading {source}"))?;

        parse_spec(&text).with_context(|| format!("parsing spec from {source}"))

    }

}

/// Parse spec text as JSON, falling back to YAML.

pub fn parse_spec(text: &str) -> Result<Value> {

    if let Ok(v) = serde_json::from_str::<Value>(text) {

        return Ok(v);

    }

    let v: Value = serde_yaml::from_str(text).context("spec is neither valid JSON nor YAML")?;

    Ok(v)

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn parses_json_and_yaml() {

        let json = r#"{"openapi":"3.0.0"}"#;

        assert_eq!(parse_spec(json).unwrap()["openapi"], "3.0.0");

        let yaml = "openapi: 3.1.0\ninfo:\n  title: t\n";

        let v = parse_spec(yaml).unwrap();

        assert_eq!(v["openapi"], "3.1.0");

        assert_eq!(v["info"]["title"], "t");

    }

    #[test]

    fn rejects_garbage() {

        assert!(parse_spec("\u{1}\u{2}not a spec at all: [").is_err());

    }

}