229 lines
7.4 KiB
Rust
229 lines
7.4 KiB
Rust
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// Handler for post duplicates.
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use crate::client::json;
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use crate::server::RequestExt;
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use crate::subreddit::{can_access_quarantine, quarantine};
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use crate::utils::{error, filter_posts, get_filters, parse_post, template, Post, Preferences};
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use askama::Template;
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use hyper::{Body, Request, Response};
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use serde_json::Value;
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use std::borrow::ToOwned;
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use std::collections::HashSet;
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use std::vec::Vec;
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/// DuplicatesParams contains the parameters in the URL.
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struct DuplicatesParams {
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before: String,
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after: String,
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sort: String,
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}
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/// DuplicatesTemplate defines an Askama template for rendering duplicate
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/// posts.
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#[derive(Template)]
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#[template(path = "duplicates.html")]
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struct DuplicatesTemplate {
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/// params contains the relevant request parameters.
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params: DuplicatesParams,
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/// post is the post whose ID is specified in the reqeust URL. Note that
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/// this is not necessarily the "original" post.
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post: Post,
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/// duplicates is the list of posts that, per Reddit, are duplicates of
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/// Post above.
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duplicates: Vec<Post>,
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/// prefs are the user preferences.
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prefs: Preferences,
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/// url is the request URL.
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url: String,
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/// num_posts_filtered counts how many posts were filtered from the
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/// duplicates list.
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num_posts_filtered: u64,
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/// all_posts_filtered is true if every duplicate was filtered. This is an
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/// edge case but can still happen.
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all_posts_filtered: bool,
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}
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/// Make the GET request to Reddit. It assumes `req` is the appropriate Reddit
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/// REST endpoint for enumerating post duplicates.
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pub async fn item(req: Request<Body>) -> Result<Response<Body>, String> {
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let path: String = format!("{}.json?{}&raw_json=1", req.uri().path(), req.uri().query().unwrap_or_default());
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let sub = req.param("sub").unwrap_or_default();
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let quarantined = can_access_quarantine(&req, &sub);
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// Log the request in debugging mode
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#[cfg(debug_assertions)]
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dbg!(req.param("id").unwrap_or_default());
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// Send the GET, and await JSON.
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match json(path, quarantined).await {
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// Process response JSON.
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Ok(response) => {
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let filters = get_filters(&req);
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let post = parse_post(&response[0]["data"]["children"][0]).await;
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let (duplicates, num_posts_filtered, all_posts_filtered) = parse_duplicates(&response[1], &filters).await;
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// These are the values for the "before=", "after=", and "sort="
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// query params, respectively.
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let mut before: String = String::new();
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let mut after: String = String::new();
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let mut sort: String = String::new();
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// FIXME: We have to perform a kludge to work around a Reddit API
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// bug.
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//
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// The JSON object in "data" will never contain a "before" value so
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// it is impossible to use it to determine our position in a
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// listing. We'll make do by getting the ID of the first post in
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// the listing, setting that as our "before" value, and ask Reddit
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// to give us a batch of duplicate posts up to that post.
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//
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// Likewise, if we provide a "before" request in the GET, the
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// result won't have an "after" in the JSON, in addition to missing
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// the "before." So we will have to use the final post in the list
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// of duplicates.
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//
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// That being said, we'll also need to capture the value of the
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// "sort=" parameter as well, so we will need to inspect the
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// query key-value pairs anyway.
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let l = duplicates.len();
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if l > 0 {
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// This gets set to true if "before=" is one of the GET params.
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let mut have_before: bool = false;
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// This gets set to true if "after=" is one of the GET params.
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let mut have_after: bool = false;
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// Inspect the query key-value pairs. We will need to record
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// the value of "sort=", along with checking to see if either
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// one of "before=" or "after=" are given.
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//
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// If we're in the middle of the batch (evidenced by the
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// presence of a "before=" or "after=" parameter in the GET),
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// then use the first post as the "before" reference.
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//
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// We'll do this iteratively. Better than with .map_or()
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// since a closure will continue to operate on remaining
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// elements even after we've determined one of "before=" or
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// "after=" (or both) are in the GET request.
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//
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// In practice, here should only ever be one of "before=" or
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// "after=" and never both.
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let query_str = req.uri().query().unwrap_or_default().to_string();
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if !query_str.is_empty() {
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for param in query_str.split('&') {
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let kv: Vec<&str> = param.split('=').collect();
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if kv.len() < 2 {
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// Reject invalid query parameter.
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continue;
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}
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let key: &str = kv[0];
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match key {
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"before" => have_before = true,
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"after" => have_after = true,
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"sort" => {
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let val: &str = kv[1];
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match val {
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"new" | "num_comments" => sort = val.to_string(),
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_ => {}
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}
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}
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_ => {}
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}
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}
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}
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if have_after {
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before = "t3_".to_owned();
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before.push_str(&duplicates[0].id);
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}
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// Address potentially missing "after". If "before=" is in the
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// GET, then "after" will be null in the JSON (see FIXME
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// above).
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if have_before {
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// The next batch will need to start from one after the
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// last post in the current batch.
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after = "t3_".to_owned();
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after.push_str(&duplicates[l - 1].id);
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// Here is where things get terrible. Notice that we
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// haven't set `before`. In order to do so, we will
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// need to know if there is a batch that exists before
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// this one, and doing so requires actually fetching the
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// previous batch. In other words, we have to do yet one
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// more GET to Reddit. There is no other way to determine
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// whether or not to define `before`.
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//
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// We'll mitigate that by requesting at most one duplicate.
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let new_path: String = format!(
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"{}.json?before=t3_{}&sort={}&limit=1&raw_json=1",
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req.uri().path(),
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&duplicates[0].id,
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if sort.is_empty() { "num_comments".to_string() } else { sort.clone() }
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);
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match json(new_path, true).await {
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Ok(response) => {
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if !response[1]["data"]["children"].as_array().unwrap_or(&Vec::new()).is_empty() {
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before = "t3_".to_owned();
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before.push_str(&duplicates[0].id);
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}
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}
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Err(msg) => {
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// Abort entirely if we couldn't get the previous
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// batch.
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return error(req, msg).await;
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}
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}
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} else {
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after = response[1]["data"]["after"].as_str().unwrap_or_default().to_string();
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}
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}
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let url = req.uri().to_string();
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template(DuplicatesTemplate {
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params: DuplicatesParams { before, after, sort },
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post,
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duplicates,
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prefs: Preferences::new(req),
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url,
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num_posts_filtered,
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all_posts_filtered,
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})
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}
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// Process error.
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Err(msg) => {
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if msg == "quarantined" {
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let sub = req.param("sub").unwrap_or_default();
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quarantine(req, sub)
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} else {
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error(req, msg).await
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}
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}
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}
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}
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// DUPLICATES
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async fn parse_duplicates(json: &serde_json::Value, filters: &HashSet<String>) -> (Vec<Post>, u64, bool) {
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let post_duplicates: &Vec<Value> = &json["data"]["children"].as_array().map_or(Vec::new(), ToOwned::to_owned);
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let mut duplicates: Vec<Post> = Vec::new();
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// Process each post and place them in the Vec<Post>.
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for val in post_duplicates.iter() {
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let post: Post = parse_post(val).await;
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duplicates.push(post);
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}
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let (num_posts_filtered, all_posts_filtered) = filter_posts(&mut duplicates, filters);
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(duplicates, num_posts_filtered, all_posts_filtered)
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}
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