//! Who belongs to which group, kept by portal itself.
//!
//! A membership is a case: one record per (group, person) in the
//! built-in `portal_memberships` bucket, `invited` until the person is
//! seen, `active` from then on, `removed` when a desk takes them out.
//! A desk invite writes one, a state that `grants` a group writes one,
//! the first person and the people the content names as responsible
//! get theirs at start. Nothing here talks to an identity provider:
//! the provider says who someone is, and this says what they belong
//! to. At sign-in, the person's active memberships become their groups,
//! and the access policy (Cedar, `access.rs`) sees them as the parents
//! of the `User` entity, exactly as it saw a `groups` claim before.
//!
//! **A person is their phone number first, their email second.** A
//! provider that verifies phone numbers (Vipps) makes the number the
//! surest thing a record can hold; a form that collected an address
//! still matches on it. A record's key is the group and whichever of
//! the two it has, so a second invite of the same person into the same
//! group finds the first.
#![cfg(feature = "ssr")]

use serde::{Deserialize, Serialize};

use crate::answers::Answer;

pub const BUCKET: &str = "portal_memberships";
pub const INVITED: &str = "invited";
pub const ACTIVE: &str = "active";
pub const REMOVED: &str = "removed";
/// Stamped on moves nobody at a desk made.
pub const BY: &str = "portal";

/// The country a phone number without one is in, as a calling code.
fn default_country() -> String {
    std::env::var("PHONE_COUNTRY").ok().filter(|c| !c.trim().is_empty()).unwrap_or_else(|| "+47".to_string())
}

/// Who a person is, as far as a record or a session knows.
#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
pub struct Identity {
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub sub: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub phone: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub email: Option<String>,
}

/// A phone number as one string for everyone: digits with a leading
/// `+` and a country code, `+4791234567`. Spaces, dots and dashes go;
/// `00` becomes `+`; a bare national number gets the site's country.
/// `None` for anything that is not a number.
pub fn normalize_phone(raw: &str, country: &str) -> Option<String> {
    let mut digits: String = raw.trim().chars().filter(|c| c.is_ascii_digit()).collect();
    let trimmed = raw.trim();
    if digits.is_empty() || digits.len() < 5 || digits.len() > 15 {
        return None;
    }
    if trimmed.starts_with('+') {
        return Some(format!("+{digits}"));
    }
    if let Some(rest) = digits.strip_prefix("00") {
        return Some(format!("+{rest}"));
    }
    if trimmed.starts_with('(') && !trimmed.contains('+') {
        digits = digits.trim_start_matches('0').to_string();
    }
    Some(format!("{}{digits}", country.trim()))
}

fn normalize_email(raw: &str) -> Option<String> {
    let e = raw.trim().trim_start_matches("mailto:").trim().to_lowercase();
    (e.contains('@') && !e.contains(char::is_whitespace)).then_some(e)
}

impl Identity {
    /// From what a form collected: the first phone-like field and the
    /// first email-like field, by the names forms use for them.
    pub fn from_responses(responses: &serde_json::Value) -> Self {
        let field = |names: &[&str]| {
            names
                .iter()
                .find_map(|n| responses.get(*n).and_then(|v| v.as_str()))
                .map(str::trim)
                .filter(|s| !s.is_empty())
                .map(String::from)
        };
        let country = default_country();
        Identity {
            sub: None,
            phone: field(&["phone", "telefon", "tel", "mobil", "mobile", "phone_number"]).and_then(|p| normalize_phone(&p, &country)),
            email: field(&["email", "epost", "e-post", "mail"]).and_then(|e| normalize_email(&e)),
        }
    }

    pub fn from_user(user: &crate::auth::User) -> Self {
        let country = default_country();
        Identity {
            sub: Some(user.sub.clone()),
            phone: user.phone.as_deref().and_then(|p| normalize_phone(p, &country)),
            email: user.email.as_deref().and_then(normalize_email),
        }
    }

    /// One person given as one string: a phone number if it reads as
    /// one, else an address.
    pub fn from_contact(contact: &str) -> Self {
        let country = default_country();
        match normalize_email(contact) {
            Some(email) => Identity { sub: None, phone: None, email: Some(email) },
            None => Identity { sub: None, phone: normalize_phone(contact, &country), email: None },
        }
    }

    /// What a membership record is keyed by: the phone number, else the
    /// address, else the provider's subject. `None` when there is
    /// nothing to know the person by.
    pub fn key(&self) -> Option<String> {
        self.phone
            .as_deref()
            .or(self.email.as_deref())
            .or(self.sub.as_deref())
            .map(|k| k.chars().map(|c| if c.is_ascii_alphanumeric() || c == '-' || c == '_' { c } else { '_' }).collect())
    }

    /// Whether a record about `other` is about this person: the same
    /// subject, phone number or address, any one of them.
    pub fn matches(&self, other: &Identity) -> bool {
        let same = |a: &Option<String>, b: &Option<String>| a.is_some() && a == b;
        same(&self.sub, &other.sub) || same(&self.phone, &other.phone) || same(&self.email, &other.email)
    }

    /// What is worth writing on a record from a login: everything the
    /// provider verified that the record did not have.
    fn merged_from(&self, seen: &Identity) -> Identity {
        Identity {
            sub: self.sub.clone().or_else(|| seen.sub.clone()),
            phone: self.phone.clone().or_else(|| seen.phone.clone()),
            email: self.email.clone().or_else(|| seen.email.clone()),
        }
    }
}

/// One record's id: the group and the person's key.
pub fn record_id(group: &str, key: &str) -> String {
    format!("{}.{key}", group.trim())
}

/// The identity a record holds.
pub fn identity_of(answer: &Answer) -> Identity {
    Identity {
        sub: answer.responses.get("sub").and_then(|v| v.as_str()).filter(|s| !s.is_empty()).map(String::from),
        phone: answer.responses.get("phone").and_then(|v| v.as_str()).filter(|s| !s.is_empty()).map(String::from),
        email: answer.responses.get("email").and_then(|v| v.as_str()).filter(|s| !s.is_empty()).map(String::from),
    }
}

pub fn group_of(answer: &Answer) -> String {
    answer.responses.get("group").and_then(|v| v.as_str()).unwrap_or_default().to_string()
}

/// The groups `who` is an active member of, from every record.
pub fn groups_of(records: &[Answer], who: &Identity) -> Vec<String> {
    let mut groups: Vec<String> = records
        .iter()
        .filter(|a| a.state == ACTIVE && identity_of(a).matches(who))
        .map(group_of)
        .filter(|g| !g.is_empty())
        .collect();
    groups.sort();
    groups.dedup();
    groups
}

async fn store(state: &crate::server::AppState) -> anyhow::Result<async_nats::jetstream::kv::Store> {
    match state.jetstream.get_key_value(BUCKET).await {
        Ok(store) => Ok(store),
        Err(_) => Ok(state
            .jetstream
            .create_key_value(async_nats::jetstream::kv::Config { bucket: BUCKET.to_string(), ..Default::default() })
            .await?),
    }
}

/// Every membership record.
pub async fn all(state: &crate::server::AppState) -> Vec<Answer> {
    let Ok(store) = state.jetstream.get_key_value(BUCKET).await else { return Vec::new() };
    let keys: Vec<String> = {
        use futures::TryStreamExt;
        match store.keys().await {
            Ok(keys) => keys.try_collect().await.unwrap_or_default(),
            Err(_) => Vec::new(),
        }
    };
    let mut out = Vec::new();
    for key in keys {
        if let Ok(Some(bytes)) = store.get(&key).await {
            if let Ok(answer) = serde_json::from_slice::<Answer>(&bytes) {
                out.push(answer);
            }
        }
    }
    out
}

/// Moves one record the way a desk button would: through the event
/// log, onto the projection, out on the answers subject.
async fn move_to(state: &crate::server::AppState, store: &async_nats::jetstream::kv::Store, mut answer: Answer, target: &str, by: &str) -> anyhow::Result<Answer> {
    let aggregates = state.aggregates.load();
    let schema = aggregates.get(BUCKET).ok_or_else(|| anyhow::anyhow!("no {BUCKET} schema"))?;
    let now_ms = chrono::Utc::now().timestamp_millis();
    let payload = serde_json::json!({ "to": target, "item": answer.id, "by": by });
    crate::answers::transition_or_reseed(&state.jetstream, schema, &answer.id, target, &answer.state, payload.clone(), now_ms)
        .await
        .map_err(|e| anyhow::anyhow!("{e}"))?;
    answer.state = target.to_string();
    answer.decided_ms = Some(now_ms);
    answer.decided_by = Some(by.to_string());
    store.put(&answer.id, serde_json::to_vec(&answer)?.into()).await?;
    let parent_hashes = vec![answer.id.clone()];
    let chain_hash = crate::chain::hash_node(&answer.question_id, &parent_hashes, &payload, now_ms);
    let event = crate::events::AnswerSubmitted {
        chain_hash,
        parent_hashes,
        question_id: answer.question_id.clone(),
        alternative: target.to_string(),
        responses: payload,
        timestamp_ms: now_ms,
        storyline: answer.storyline,
    };
    let _ = crate::events::emit_answer_submitted(&state.nats, &event).await;
    Ok(answer)
}

/// Puts a person in a group, or finds them there. A new record starts
/// `invited`; a removed one is invited again; an invited or active one
/// is left as it is, so a second grant costs nothing. `created` in
/// what comes back says whether the person had a place already.
pub async fn grant(state: &crate::server::AppState, group: &str, name: &str, who: &Identity, by: &str) -> anyhow::Result<crate::people::Invited> {
    let key = who.key().ok_or_else(|| anyhow::anyhow!("a membership needs a phone number or an address to know the person by"))?;
    let store = store(state).await?;
    // The person's record in this group, however it was keyed: a desk
    // that invited by address and a decision that granted by phone
    // number are talking about one person once a sign-in has joined
    // the two, and must not make two.
    let existing: Option<Answer> = all(state).await.into_iter().find(|a| group_of(a) == group.trim() && identity_of(a).matches(who));
    let id = existing.as_ref().map(|a| a.id.clone()).unwrap_or_else(|| record_id(group, &key));
    let now_ms = chrono::Utc::now().timestamp_millis();
    let invited = |created: bool| crate::people::Invited {
        username: key.clone(),
        display_name: name.to_string(),
        email: who.email.clone().unwrap_or_default(),
        group: group.to_string(),
        reset_link: None,
        link_expires_ms: None,
        created,
        mail: None,
        fields: Default::default(),
        already_member: !created,
    };
    match existing {
        Some(answer) if answer.state == REMOVED => {
            move_to(state, &store, answer, INVITED, by).await?;
            Ok(invited(true))
        }
        Some(_) => Ok(invited(false)),
        None => {
            let responses = serde_json::json!({
                "name": name, "group": group, "by": by,
                "phone": who.phone, "email": who.email, "sub": who.sub,
            });
            crate::answers::store_answer(&state.jetstream, &state.aggregates.load(), BUCKET, id, "/", "Membership", &responses, now_ms, 0).await?;
            Ok(invited(true))
        }
    }
}

/// Takes a person out of a group: the record moves to `removed` and
/// stays, so the desk can see who was in and put them back.
pub async fn revoke(state: &crate::server::AppState, group: &str, who: &Identity, by: &str) -> anyhow::Result<bool> {
    let Some(key) = who.key() else { return Ok(false) };
    let store = store(state).await?;
    let id = record_id(group, &key);
    let Some(answer) = store.get(&id).await?.and_then(|b| serde_json::from_slice::<Answer>(&b).ok()) else {
        return Ok(false);
    };
    if answer.state == REMOVED {
        return Ok(false);
    }
    move_to(state, &store, answer, REMOVED, by).await?;
    Ok(true)
}

/// Someone signed in: every invitation that was for them is now a
/// membership, with what the provider verified written on the record,
/// and their active groups come back to be their groups for the
/// session. Their `sub` is remembered, so the next login matches on
/// it before anything else.
pub async fn on_signed_in(state: &crate::server::AppState, user: &crate::auth::User) -> Vec<String> {
    let who = Identity::from_user(user);
    let records = all(state).await;
    let Ok(store) = store(state).await else { return groups_of(&records, &who) };
    let mut settled = Vec::with_capacity(records.len());
    for answer in records {
        let held = identity_of(&answer);
        if !held.matches(&who) {
            settled.push(answer);
            continue;
        }
        let merged = held.merged_from(&who);
        let mut answer = answer;
        if merged != held {
            if let Some(map) = answer.responses.as_object_mut() {
                map.insert("sub".into(), serde_json::json!(merged.sub));
                map.insert("phone".into(), serde_json::json!(merged.phone));
                map.insert("email".into(), serde_json::json!(merged.email));
            }
            if let Ok(bytes) = serde_json::to_vec(&answer) {
                let _ = store.put(&answer.id, bytes.into()).await;
            }
        }
        if answer.state == INVITED {
            match move_to(state, &store, answer.clone(), ACTIVE, BY).await {
                Ok(active) => {
                    tracing::info!(group = %group_of(&active), user = %user.username, "an invitation became a membership");
                    settled.push(active);
                }
                Err(e) => {
                    tracing::warn!(id = %answer.id, "an invitation could not become a membership: {e}");
                    settled.push(answer);
                }
            }
        } else {
            settled.push(answer);
        }
    }
    groups_of(&settled, &who)
}

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

    fn record(group: &str, state: &str, phone: Option<&str>, email: Option<&str>, sub: Option<&str>) -> Answer {
        Answer {
            id: record_id(group, "k"),
            question_id: "/".into(),
            alternative: "Membership".into(),
            responses: serde_json::json!({ "group": group, "phone": phone, "email": email, "sub": sub, "name": "X" }),
            state: state.into(),
            submitted_ms: 0,
            storyline: 0,
            decided_ms: None,
            decided_by: None,
            notes: Vec::new(),
        }
    }

    #[test]
    fn a_phone_number_is_one_string_for_everyone() {
        assert_eq!(normalize_phone("912 34 567", "+47"), Some("+4791234567".into()));
        assert_eq!(normalize_phone("+47 912-34-567", "+47"), Some("+4791234567".into()));
        assert_eq!(normalize_phone("004791234567", "+47"), Some("+4791234567".into()));
        assert_eq!(normalize_phone("91234567", "+46"), Some("+4691234567".into()));
        assert_eq!(normalize_phone("kari@vel.no", "+47"), None);
        assert_eq!(normalize_phone("123", "+47"), None);
    }

    #[test]
    fn a_person_is_their_phone_first_and_their_address_second() {
        let both = Identity::from_responses(&serde_json::json!({ "name": "Kari", "telefon": "912 34 567", "email": "Kari@Vel.no" }));
        assert_eq!(both.key().as_deref(), Some("_4791234567"));
        assert_eq!(both.email.as_deref(), Some("kari@vel.no"));
        let mail_only = Identity::from_responses(&serde_json::json!({ "epost": "Kari@Vel.no" }));
        assert_eq!(mail_only.key().as_deref(), Some("kari_vel_no"));
        assert_eq!(Identity::from_contact("mailto:Post@Vel.no").email.as_deref(), Some("post@vel.no"));
        assert_eq!(Identity::from_contact("912 34 567").phone.as_deref(), Some("+4791234567"));
        assert!(Identity::default().key().is_none());
    }

    #[test]
    fn a_record_is_about_a_person_by_any_one_of_sub_phone_or_email() {
        let kari = Identity { sub: Some("abc".into()), phone: Some("+4791234567".into()), email: Some("kari@vel.no".into()) };
        assert!(Identity { sub: None, phone: Some("+4791234567".into()), email: None }.matches(&kari));
        assert!(Identity { sub: None, phone: None, email: Some("kari@vel.no".into()) }.matches(&kari));
        assert!(Identity { sub: Some("abc".into()), phone: None, email: Some("old@vel.no".into()) }.matches(&kari));
        assert!(!Identity { sub: None, phone: Some("+4799999999".into()), email: Some("ola@vel.no".into()) }.matches(&kari));
        assert!(!Identity::default().matches(&kari));
    }

    #[test]
    fn only_active_memberships_are_groups() {
        let kari = Identity { sub: None, phone: Some("+4791234567".into()), email: Some("kari@vel.no".into()) };
        let records = vec![
            record("styret", ACTIVE, Some("+4791234567"), None, None),
            record("kasserer", INVITED, None, Some("kari@vel.no"), None),
            record("trafikk", REMOVED, Some("+4791234567"), None, None),
            record("medlemmer", ACTIVE, None, Some("kari@vel.no"), None),
            record("styret", ACTIVE, Some("+4799999999"), None, None),
        ];
        assert_eq!(groups_of(&records, &kari), vec!["medlemmer", "styret"]);
    }
}