// This file was originally based on
// <https://github.com/timothee-haudebourg/json-ld/blob/0.12.1/core/src/loader/reqwest/link.rs>.
//
// Copyright (C) 2022 Timothée Haudebourg et al.
// Licensed under either the Apache License, Version 2.0; or the MIT License.
// See <https://github.com/timothee-haudebourg/json-ld/tree/0.12.1> for details.
//
// Heavily modified by anna <owo@fef.moe> to use nyanoblog's own Structured Header
// parser and accept the `application/activity+json` MIME type as proper JSON-LD.

use iref::{IriRef, IriRefBuf};
use reqwest::header::HeaderValue;
use std::str::FromStr;

use crate::util::header::{Item, ParseHeader, ParseOptions};

pub struct Link {
    href: IriRefBuf,
    rel: Option<String>,
    typ: Option<String>,
}

impl Link {
    pub fn from_header(value: &HeaderValue) -> Option<Self> {
        let item = Item::parse_from_header(value, ParseOptions::link_header()).ok()?;
        let href = IriRefBuf::from_str(item.as_url()?).ok()?;
        let rel = item.param("rel").and_then(|rel| rel.as_string());
        let typ = item.param("type").and_then(|typ| typ.as_string());
        Some(Link { href, rel, typ })
    }

    pub fn href(&self) -> IriRef {
        self.href.as_iri_ref()
    }

    pub fn rel(&self) -> Option<&str> {
        self.rel.as_deref()
    }

    pub fn typ(&self) -> Option<&str> {
        self.typ.as_deref()
    }

    pub fn is_proper_json_ld(&self) -> bool {
        self.typ()
            .filter(|t| ["application/activity+json", "application/ld+json"].contains(t))
            .is_some()
    }
}

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

    fn mklink(header_value: &'static str) -> Option<Link> {
        Link::from_header(&HeaderValue::from_str(header_value).unwrap())
    }

    #[test]
    fn parse_link_1() {
        let link = mklink(
            "<http://www.example.org/context>; rel=\"context\"; type=\"application/ld+json\"",
        )
        .unwrap();
        assert_eq!(link.href(), "http://www.example.org/context");
        assert_eq!(link.rel(), Some("context"));
        assert_eq!(link.typ(), Some("application/ld+json"))
    }

    #[test]
    fn parse_link_2() {
        let link = mklink(
            "<http://www.example.org/context>; rel =  \"context\" ; type=\"application/ld+json\"  ; foo=\"bar\"",
        )
        .unwrap();
        assert_eq!(link.href(), "http://www.example.org/context");
        assert_eq!(link.rel(), Some("context"));
        assert_eq!(link.typ(), Some("application/ld+json"))
    }

    #[test]
    fn parse_link_3() {
        let link = mklink("<http://www.example.org/context>").unwrap();
        assert_eq!(link.href(), "http://www.example.org/context")
    }

    #[test]
    fn is_proper_json_ld() {
        let link = mklink(
            "<http://www.example.org/context>; rel=\"context\"; type=\"application/ld+json\"",
        )
        .unwrap();
        assert!(link.is_proper_json_ld());

        let link = mklink(
            "<http://www.example.org/context>; rel=\"context\"; type=\"application/activity+json\"",
        )
        .unwrap();
        assert!(link.is_proper_json_ld());

        let link =
            mklink("<http://www.example.org/context>; rel=\"context\"; type=\"application/json\"")
                .unwrap();
        assert!(!link.is_proper_json_ld());
    }
}