1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150

use chrono::{Duration, NaiveDateTime, TimeZone, Utc};
use lazy_static::lazy_static;
use regex::Regex;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

pub async fn archive_url(url: &str) -> Result<ArchivingResult, ArchiveError> {
    // Check to see if there's an existing archive of the requested URL.
    let latest_snapshot = fetch_latest_snapshot(url).await;
    if let Ok(ref snapshot) = latest_snapshot {
        // Only accept the existing snapshot if it was made recently.
        if (Utc::now() - Duration::days(90)).naive_utc() < snapshot.last_archived {
            return latest_snapshot;
        }
    }

    // Request a new snapshot of the URL.
    let resp = reqwest::get(format!("https://web.archive.org/save/{}", url))
        .await
        .map_err(|err| ArchiveError::Unknown(err.to_string()))?;
    let archive_url: Result<String, ArchiveError> = match resp.status().as_u16() {
        // Return the redirected URL (which is the archive snapshot URL).
        200 => Ok(resp.url().clone().to_string()),
        404 => {
            // Sometimes, the snapshot URL returns a 404, even though the archival was successful.
            // Probably due to a race condition in the Wayback machine; these URLs do (eventually) exist.
            if resp.url().path().starts_with("/web") {
                Ok(resp.url().to_string())
            } else {
                Err(ArchiveError::Unknown(format!(
                    "Unexpected HTTP 404 at {:#?}",
                    resp.url().to_string()
                )))
            }
        }
        509 => Err(ArchiveError::BandwidthExceeded),
        // There may be more status codes that indicate archive failure, but these were the most common.
        403 | 520 | 523 => Err(ArchiveError::UnableToArchive),
        _ => {
            dbg!(&resp);
            Err(ArchiveError::Unknown(format!(
                "Got status {}: {:#?}",
                resp.status(),
                resp
            )))
        }
    };
    let result = archive_url.and_then(|url| {
        Ok(ArchivingResult {
            last_archived: timestamp_from_archive_url(&url)?,
            url: Some(url),
            existing_snapshot: false,
        })
    });
    match result {
        Err(ArchiveError::UnableToArchive) => {
            // If we weren't able to archive the URL, but a valid (if old) snapshot exists,
            // then return that older snapshot.
            latest_snapshot.map_err(|_| ArchiveError::UnableToArchive)
        }
        _ => result,
    }
}

fn timestamp_from_archive_url(url: &str) -> Result<NaiveDateTime, ArchiveError> {
    lazy_static! {
        static ref RE: Regex = Regex::new(r"/web/(\d+)/").unwrap();
    }
    let timestamp_url_component = RE
        .captures(url)
        .and_then(|cap| cap.get(1).map(|ts_str| ts_str.as_str()))
        .ok_or_else(|| ArchiveError::ParseError("unable to extract timestamp from url".into()))?;
    parse_wayback_timestamp(timestamp_url_component)
}

async fn fetch_latest_snapshot(url: &str) -> Result<ArchivingResult, ArchiveError> {
    let resp = reqwest::get(format!("http://archive.org/wayback/available?url={}", url))
        .await
        .map_err(|err| ArchiveError::Unknown(err.to_string()))?
        .json::<WaybackAvailabilityResponse>()
        .await
        .map_err(|err| ArchiveError::ParseError(err.to_string()))?;

    if let Some(snapshots) = resp.archived_snapshots {
        if let Some((_, latest)) = snapshots
            .iter()
            .max_by_key(|(_, snapshot)| &snapshot.timestamp)
        {
            return Ok(ArchivingResult {
                existing_snapshot: true,
                last_archived: parse_wayback_timestamp(&latest.timestamp)?,
                url: Some(latest.url.clone()),
            });
        }
    }
    Err(ArchiveError::NoExistingSnapshot)
}

fn parse_wayback_timestamp(ts: &str) -> Result<NaiveDateTime, ArchiveError> {
    let naive_utc = NaiveDateTime::parse_from_str(ts, "%Y%m%d%H%M%S")
        .map_err(|err| ArchiveError::ParseError(err.to_string()))?;
    Ok(Utc.from_utc_datetime(&naive_utc).naive_local())
}

#[derive(Deserialize, Debug)]
struct WaybackAvailabilityResponse {
    url: String,
    archived_snapshots: Option<HashMap<String, WaybackSnapshot>>,
}

#[derive(Deserialize, Debug)]
struct WaybackSnapshot {
    status: String,
    available: bool,
    url: String,
    timestamp: String,
}

#[derive(Deserialize, Serialize, Debug)]
pub struct ArchivingResult {
    pub url: Option<String>,
    pub last_archived: NaiveDateTime,
    #[serde(skip)]
    pub existing_snapshot: bool,
}

#[derive(Debug, PartialEq)]
pub enum ArchiveError {
    BandwidthExceeded,
    UnableToArchive,
    NoExistingSnapshot,
    ParseError(String),
    Unknown(String),
}

impl std::fmt::Display for ArchiveError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            ArchiveError::BandwidthExceeded => write!(f, "Bandwidth Exceeded"),
            ArchiveError::UnableToArchive => {
                write!(f, "Wayback Machine unable to archive this URL")
            }
            ArchiveError::NoExistingSnapshot => write!(f, "No existing snapshots"),
            ArchiveError::ParseError(err) => write!(f, "Parse error: {}", err),
            ArchiveError::Unknown(err) => write!(f, "Unknown error: {}", err),
        }
    }
}

impl std::error::Error for ArchiveError {}