use chrono::{DateTime, Utc};
use serde::{Deserialize, Deserializer};

pub fn cohost_posts_api_url(project: impl AsRef<str>, page: u64) -> String {
    format!(
        "https://cohost.org/api/v1/project/{}/posts?page={}",
        project.as_ref(),
        page
    )
}

// Cohost doesn't give us Next links ("rel: next") for further pages, so we'll have to ALWAYS populate the rel=next field

#[derive(Debug, Clone, Deserialize)]
pub struct CohostPostsPage {
    #[serde(rename = "nItems")]
    pub number_items: usize,
    #[serde(rename = "nPages")]
    pub number_pages: u64,
    pub items: Vec<CohostPost>,
    #[serde(rename = "_links")]
    pub links: Vec<CohostPostLink>,
}

#[derive(Debug, Clone, Deserialize)]
pub struct CohostPost {
    #[serde(rename = "postId")]
    pub id: u64,
    #[serde(deserialize_with = "deserialize_null_default", default)]
    pub headline: String,
    #[serde(rename = "publishedAt")]
    pub published_at: DateTime<Utc>,
    pub cws: Vec<String>,
    pub tags: Vec<String>,
    #[serde(
        rename = "plainTextBody",
        deserialize_with = "deserialize_null_default",
        default
    )]
    pub plain_body: String,
    #[serde(
        rename = "singlePostPageUrl",
        deserialize_with = "deserialize_null_default",
        default
    )]
    pub url: String,
    #[serde(rename = "postingProject")]
    pub poster: CohostPostingProject,
    #[serde(rename = "shareTree")]
    pub share_tree: Vec<CohostPost>,
}

#[derive(Debug, Clone, Deserialize)]
pub struct CohostPostingProject {
    #[serde(rename = "projectId")]
    pub id: u64,
    #[serde(deserialize_with = "deserialize_null_default", default)]
    pub handle: String,
    #[serde(
        rename = "displayName",
        deserialize_with = "deserialize_null_default",
        default
    )]
    pub display_name: String,
    #[serde(deserialize_with = "deserialize_null_default", default)]
    pub dek: String,
    #[serde(deserialize_with = "deserialize_null_default", default)]
    pub description: String,
    #[serde(deserialize_with = "deserialize_null_default", default)]
    pub pronouns: String,
}

#[derive(Debug, Clone, Deserialize)]
pub struct CohostPostLink {
    #[serde(deserialize_with = "deserialize_null_default", default)]
    pub href: String,
    #[serde(deserialize_with = "deserialize_null_default", default)]
    pub rel: String,
    #[serde(
        rename = "type",
        deserialize_with = "deserialize_null_default",
        default
    )]
    pub t_type: String,
}

fn deserialize_null_default<'de, D, T>(deserializer: D) -> Result<T, D::Error>
where
    T: Default + Deserialize<'de>,
    D: Deserializer<'de>,
{
    let opt = Option::deserialize(deserializer)?;
    Ok(opt.unwrap_or_default())
}

#[test]
fn test_deserialize() -> Result<(), Box<dyn std::error::Error>> {
    let post_page_json = include_str!("../samples/cohost/api/v1/project_posts.json");
    let post_page_actual: CohostPostsPage = serde_json::from_str(post_page_json)?;
    assert_eq!(post_page_actual.number_items, post_page_actual.items.len());
    let post = &post_page_actual.items[0];
    assert_eq!(post.id, 149268);
    assert_eq!(post.poster.id, 32693);
    Ok(())
}

#[test]
fn test_deserialize_weird() -> Result<(), Box<dyn std::error::Error>> {
    let post_page_json = include_str!("../samples/cohost/api/v1/vogon_pathological.json");
    let _post_page_actual: CohostPostsPage = serde_json::from_str(post_page_json)?;
    Ok(())
}

#[test]
fn test_deserialize_empty() -> Result<(), Box<dyn std::error::Error>> {
    let post_page_json = include_str!("../samples/cohost/api/v1/empty_posts_age.json");
    let post_page_actual: CohostPostsPage = serde_json::from_str(post_page_json)?;
    println!("{:?}", post_page_actual);
    assert!(post_page_actual.items.is_empty());
    Ok(())
}