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// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use serde::{Deserialize, Serialize};

pub mod request;
pub mod response;

pub const PROTOCOL_V3: &str = "3.0";

/// The cohort identifies the update 'track' or 'channel', and is used to implement the tracking of
/// membership in a fractional roll-out.  This is per-application data.
///
/// This is sent to Omaha to identify the cohort that the application is in.  This is returned (with
/// possibly new values) by Omaha to indicate that the application is now in a different cohort.  On
/// the next update check for that application, the updater needs to use this newly returned cohort
/// as the one that it sends to Omaha with that application.
///
/// For more information about cohorts, see the 'cohort', 'cohorthint', and 'cohortname' attributes
/// of the Request.App object at:
///
/// https://github.com/google/omaha/blob/HEAD/doc/ServerProtocolV3.md#app-request
#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
pub struct Cohort {
    /// This is the cohort id itself.
    #[serde(rename = "cohort")]
    #[serde(skip_serializing_if = "Option::is_none")]
    pub id: Option<String>,

    #[serde(rename = "cohorthint")]
    #[serde(skip_serializing_if = "Option::is_none")]
    pub hint: Option<String>,

    #[serde(rename = "cohortname")]
    #[serde(skip_serializing_if = "Option::is_none")]
    pub name: Option<String>,
}

impl Cohort {
    /// Create a new Cohort instance from just a cohort id (channel name).
    pub fn new(id: &str) -> Cohort {
        Cohort { id: Some(id.to_string()), hint: None, name: None }
    }

    pub fn from_hint(hint: &str) -> Cohort {
        Cohort { id: None, hint: Some(hint.to_string()), name: None }
    }

    pub fn update_from_omaha(&mut self, omaha_cohort: Self) {
        // From Omaha spec:
        // If this attribute is transmitted in the response (even if the value is empty-string),
        // the client should overwrite the current cohort of this app with the sent value.
        if omaha_cohort.id.is_some() {
            self.id = omaha_cohort.id;
        }
        if omaha_cohort.hint.is_some() {
            self.hint = omaha_cohort.hint;
        }
        if omaha_cohort.name.is_some() {
            self.name = omaha_cohort.name;
        }
    }

    /// A validation function to test that a given Cohort hint or name is valid per the Omaha spec:
    ///  1-1024 ascii characters, with values in the range [\u20-\u7e].
    pub fn validate_name(name: &str) -> bool {
        !name.is_empty()
            && name.len() <= 1024
            && name.chars().all(|c| ('\u{20}'..='\u{7e}').contains(&c))
    }
}

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

    #[test]
    fn test_cohort_new() {
        let cohort = Cohort::new("my_cohort");
        assert_eq!(Some("my_cohort".to_string()), cohort.id);
        assert_eq!(None, cohort.hint);
        assert_eq!(None, cohort.name);
    }

    #[test]
    fn test_cohort_update_from_omaha() {
        let mut cohort = Cohort::from_hint("hint");
        let omaha_cohort = Cohort::new("my_cohort");
        cohort.update_from_omaha(omaha_cohort);
        assert_eq!(Some("my_cohort".to_string()), cohort.id);
        assert_eq!(Some("hint".to_string()), cohort.hint);
        assert_eq!(None, cohort.name);
    }

    #[test]
    fn test_cohort_update_from_omaha_none() {
        let mut cohort = Cohort {
            id: Some("id".to_string()),
            hint: Some("hint".to_string()),
            name: Some("name".to_string()),
        };
        let expected_cohort = cohort.clone();
        cohort.update_from_omaha(Cohort::default());
        assert_eq!(cohort, expected_cohort);
    }

    #[test]
    fn test_valid_cohort_names() {
        assert!(Cohort::validate_name("some-channel"));
        assert!(Cohort::validate_name("a"));

        let max_len_name = "a".repeat(1024);
        assert!(Cohort::validate_name(&max_len_name));
    }

    #[test]
    fn test_invalid_cohort_name_length() {
        assert!(!Cohort::validate_name(""));

        let too_long_name = "a".repeat(1025);
        assert!(!Cohort::validate_name(&too_long_name));
    }

    #[test]
    fn test_invalid_cohort_name_chars() {
        assert!(!Cohort::validate_name("some\u{09}channel"));
        assert!(!Cohort::validate_name("some\u{07f}channel"));
        assert!(!Cohort::validate_name("some\u{080}channel"));
    }
}