use chrono::{Local, NaiveDateTime};
use crypto::digest::Digest;
use crypto::sha2::Sha256;
use diesel::pg::PgConnection as PGC;
use diesel::prelude::*;
use syntect::highlighting::ThemeSet;
use syntect::html::highlighted_html_for_string;
use syntect::parsing::SyntaxSet;

use crate::schema::snippets;
use crate::schema::snippets::columns::uuid;

#[derive(Queryable, Serialize, Deserialize)]
pub struct Snippet {
    pub id: i32,
    pub title: String,
    pub body: String,
    pub created_at: Option<NaiveDateTime>,
    pub filetype: Option<String>,
    pub formatted_body: String,
    pub uuid: String,
}

#[derive(Serialize, Deserialize)]
pub struct ApiSnippet {
    pub title: String,
    pub body: String,
    pub filetype: Option<String>,
}

#[derive(Insertable, AsChangeset)]
#[table_name = "snippets"]
pub struct InsertableSnippet {
    pub title: String,
    pub body: String,
    pub filetype: Option<String>,
    pub formatted_body: String,
    pub uuid: String,
}

fn format_snippet(filetype: Option<String>, body: String) -> String {
    filetype.map_or(
        format!("<pre class='plaintext'>\n{}\n</pre>", body),
        |filetype| {
            let ps = SyntaxSet::load_defaults_newlines();
            let ts = ThemeSet::load_defaults();
            ps.find_syntax_by_extension(&filetype).map_or(
                format!("<pre class='plaintext'>\n{}\n</pre>", body),
                |syntax| {
                    let content = htmlescape::decode_html(&body).expect("Invalid HTML");
                    highlighted_html_for_string(
                        &content,
                        &ps,
                        &syntax,
                        &ts.themes["Solarized (light)"],
                    )
                },
            )
        },
    )
}

fn generate_uuid(snippet: &ApiSnippet) -> String {
    let current_timestamp = Local::now().to_string();
    let mut hasher = Sha256::new();
    hasher.input_str(&format!(
        "{}{}{}",
        snippet.title, snippet.body, current_timestamp
    ));
    hasher.result_str().to_string()
}

pub fn get(connection: &PGC, snippet_uuid: &str) -> QueryResult<Snippet> {
    snippets::table
        .filter(uuid.eq(snippet_uuid))
        .first(connection)
}

pub fn insert(snippet: ApiSnippet, connection: &PGC) -> QueryResult<Snippet> {
    let body = htmlescape::encode_minimal(&snippet.body.clone());
    let formatted_snippet = InsertableSnippet {
        filetype: snippet.filetype.clone(),
        title: snippet.title.clone(),
        body: body.clone(),
        uuid: generate_uuid(&snippet),
        formatted_body: format_snippet(snippet.filetype, body),
    };
    diesel::insert_into(snippets::table)
        .values(formatted_snippet)
        .get_result(connection)
}

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

    #[test]
    fn identical_snippets_have_different_uuids() {
        let snippet = ApiSnippet {
            title: String::from("Hello world"),
            body: String::from("Hello world"),
            filetype: None,
        };
        let uuid1 = generate_uuid(&snippet);
        let uuid2 = generate_uuid(&snippet);
        assert!(uuid1 != uuid2);
    }
}