//! `/api/schedules`: the operator's scheduled prompts.

use serde::{Deserialize, Deserializer, Serialize, Serializer};

/// One schedule as the API shows it.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema", derive(utoipa::ToSchema))]
pub struct ScheduleView {
    pub id: String,
    /// The operator's title for it.
    pub name: String,
    /// The agents it fires in, sorted.
    pub agents: Vec<String>,
    /// The prompt, delivered to each agent verbatim.
    pub body: String,
    /// The first fire time, unix seconds.
    pub anchor_unix: i64,
    /// Seconds between fires; `null` for a one-shot.
    pub interval_seconds: Option<u64>,
    pub paused: bool,
    /// The next fire time on the schedule's grid, unix seconds, computed when
    /// the response is built; `null` when paused or a one-shot whose time
    /// has passed. Says nothing about whether an agent fired an earlier one.
    pub next_fire_unix: Option<i64>,
}

/// A new schedule.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema", derive(utoipa::ToSchema))]
pub struct AddScheduleRequest {
    /// The title. Must not be empty.
    pub name: String,
    /// The agents to fire in, at least one. Each must be declared on a hive.
    pub agents: Vec<String>,
    /// The prompt, delivered verbatim. Must not be empty.
    pub body: String,
    /// The first fire time, unix seconds. Defaults to now.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub anchor_unix: Option<i64>,
    /// Seconds between fires, at least 1. Absent for a one-shot.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub interval_seconds: Option<u64>,
    #[serde(default)]
    pub paused: bool,
}

/// A partial change to one schedule; an absent field is left as it is.
#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema", derive(utoipa::ToSchema))]
pub struct EditScheduleRequest {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub name: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub body: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub anchor_unix: Option<i64>,
    /// A number sets the interval; `null` makes the schedule a one-shot.
    #[serde(default, skip_serializing_if = "IntervalEdit::is_keep")]
    #[cfg_attr(feature = "schema", schema(value_type = Option<u64>))]
    pub interval_seconds: IntervalEdit,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub paused: Option<bool>,
    /// Agents to add. Each must be declared on a hive; one already targeted
    /// is left as it is.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub add_agents: Vec<String>,
    /// Agents to remove. Each must be a current target, and at least one
    /// target must remain.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub remove_agents: Vec<String>,
}

/// What an edit does to the interval: an absent field keeps it, `null` makes
/// a one-shot, a number sets it. `Keep` is never serialized; the field is
/// left out instead.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub enum IntervalEdit {
    #[default]
    Keep,
    Set(Option<u64>),
}

impl IntervalEdit {
    #[must_use]
    pub fn is_keep(&self) -> bool {
        matches!(self, Self::Keep)
    }
}

impl Serialize for IntervalEdit {
    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
        match self {
            Self::Keep | Self::Set(None) => s.serialize_none(),
            Self::Set(Some(seconds)) => s.serialize_u64(*seconds),
        }
    }
}

impl<'de> Deserialize<'de> for IntervalEdit {
    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
        Option::<u64>::deserialize(d).map(Self::Set)
    }
}

#[cfg(test)]
mod tests {
    use super::{AddScheduleRequest, EditScheduleRequest, IntervalEdit, ScheduleView};

    /// Serialize `value`, check it against `wire`, and decode `wire` back.
    fn round_trip<T>(value: &T, wire: &str)
    where
        T: serde::Serialize + serde::de::DeserializeOwned + PartialEq + std::fmt::Debug,
    {
        assert_eq!(serde_json::to_string(value).unwrap(), wire);
        assert_eq!(&serde_json::from_str::<T>(wire).unwrap(), value);
    }

    #[test]
    fn a_view_round_trips() {
        round_trip(
            &ScheduleView {
                id: "abc".to_owned(),
                name: "standup".to_owned(),
                agents: vec!["atlas".to_owned(), "iris".to_owned()],
                body: "post the standup".to_owned(),
                anchor_unix: 1000,
                interval_seconds: Some(3600),
                paused: false,
                next_fire_unix: Some(4600),
            },
            r#"{"id":"abc","name":"standup","agents":["atlas","iris"],"body":"post the standup","anchor_unix":1000,"interval_seconds":3600,"paused":false,"next_fire_unix":4600}"#,
        );
        round_trip(
            &ScheduleView {
                id: "abc".to_owned(),
                name: "once".to_owned(),
                agents: vec!["atlas".to_owned()],
                body: "hi".to_owned(),
                anchor_unix: 0,
                interval_seconds: None,
                paused: true,
                next_fire_unix: None,
            },
            r#"{"id":"abc","name":"once","agents":["atlas"],"body":"hi","anchor_unix":0,"interval_seconds":null,"paused":true,"next_fire_unix":null}"#,
        );
    }

    /// An absent anchor or interval is left out, `paused` is always sent, and
    /// a body without `paused` decodes as not paused.
    #[test]
    fn an_add_round_trips() {
        let mut add = AddScheduleRequest {
            name: "n".to_owned(),
            agents: vec!["iris".to_owned()],
            body: "hi".to_owned(),
            anchor_unix: Some(5),
            interval_seconds: Some(60),
            paused: true,
        };
        round_trip(
            &add,
            r#"{"name":"n","agents":["iris"],"body":"hi","anchor_unix":5,"interval_seconds":60,"paused":true}"#,
        );
        add.anchor_unix = None;
        add.interval_seconds = None;
        add.paused = false;
        round_trip(
            &add,
            r#"{"name":"n","agents":["iris"],"body":"hi","paused":false}"#,
        );
        assert_eq!(
            serde_json::from_str::<AddScheduleRequest>(
                r#"{"name":"n","agents":["iris"],"body":"hi"}"#
            )
            .unwrap(),
            add
        );
    }

    /// An edit sends only what it changes: `Keep` and empty agent lists are
    /// left out, and a one-shot is an explicit `null`.
    #[test]
    fn an_edit_round_trips() {
        round_trip(&EditScheduleRequest::default(), "{}");
        round_trip(
            &EditScheduleRequest {
                name: Some("hi".to_owned()),
                ..EditScheduleRequest::default()
            },
            r#"{"name":"hi"}"#,
        );
        round_trip(
            &EditScheduleRequest {
                interval_seconds: IntervalEdit::Set(None),
                ..EditScheduleRequest::default()
            },
            r#"{"interval_seconds":null}"#,
        );
        round_trip(
            &EditScheduleRequest {
                anchor_unix: Some(5),
                interval_seconds: IntervalEdit::Set(Some(60)),
                add_agents: vec!["iris".to_owned()],
                remove_agents: vec!["atlas".to_owned()],
                ..EditScheduleRequest::default()
            },
            r#"{"anchor_unix":5,"interval_seconds":60,"add_agents":["iris"],"remove_agents":["atlas"]}"#,
        );
        round_trip(
            &EditScheduleRequest {
                body: Some("b".to_owned()),
                paused: Some(true),
                ..EditScheduleRequest::default()
            },
            r#"{"body":"b","paused":true}"#,
        );
    }
}