//! The CI metrics poller's read-only forge account, [`LOGIN`]: created here
//! with the admin API, put in a [`TEAM`] in every organisation that reads the
//! Actions unit of each of its repos (including ones created later), and
//! given one token, stored at
//! `swarm_secret_client::ci_metrics::forge_token_path`, where the poller reads
//! it under its own store identity to list CI runs.
//!
//! A public repo's runs need no grant. A private repo owned by a user gets
//! none: the forge grants a user's repo only to a collaborator, and a
//! collaborator reads every unit, code included.
//!
//! The token decision is [`super::agent_token`]'s, under this module's name
//! and scopes, so a stored token the forge still lists with the same last
//! eight characters and scopes is kept, and a pass whose reads fail queues
//! nothing.

use std::sync::Arc;

use anyhow::{Context, Result, bail};
use forgejo_api::structs::{
    CreateTeamOption, CreateTeamOptionPermission, EditTeamOption, EditTeamOptionPermission,
    RepoSearchQuery, Team, TeamPermission,
};
use forgejo_api::{Auth, Forgejo};
use swarm_secret_client::ci_metrics::forge_token_path;
use swarm_secret_client::forge;

use super::agent_token::{Decision, Observed, classify_named, is_not_found};
use super::hive_token::TeamSeen;
use super::{Client, folds_into_success};

/// The poller's forge login.
pub const LOGIN: &str = "ci-metrics";

/// The forge's name for the account's one token.
pub const TOKEN_NAME: &str = "swarm-ci-metrics";

/// What the token may do: read repositories, which the runs list is filed
/// under. Which repositories is the account's business: public ones, and
/// those its [`TEAM`]s reach.
pub const TOKEN_SCOPES: &str = "read:repository";

/// The team in each organisation the account is the one member of.
const TEAM: &str = "ci-metrics";

const TEAM_DESCRIPTION: &str = "hyperhive CI metrics — read on every repo's Actions runs";

/// The one unit the team reads.
const TEAM_UNITS: [&str; 1] = ["repo.actions"];

/// Organisations per page of the admin listing.
const ORG_PAGE: u32 = 50;

/// How often [`spawn`] re-checks the account, its teams and its token.
const RECONCILE_INTERVAL: std::time::Duration = std::time::Duration::from_mins(5);

/// The email this module creates the account with, and the one it requires
/// before acting on an account named [`LOGIN`]. Under its own domain, so it
/// equals no agent's or hive's account email.
const EMAIL: &str = "ci-metrics@services.hyperhive.local";

/// Whether `t` has every setting [`Client::ensure_ci_metrics_team`] gives it.
fn team_matches(t: &Team) -> bool {
    t.units
        .as_deref()
        .is_some_and(|units| units.iter().map(String::as_str).eq(TEAM_UNITS))
        && t.permission == Some(TeamPermission::Read)
        && t.includes_all_repositories == Some(true)
        && t.can_create_org_repo == Some(false)
        && t.description.as_deref() == Some(TEAM_DESCRIPTION)
}

/// Whether a pass that found `seen`, and `granted` for whether every
/// organisation's [`TEAM`] is as the job leaves it with the account in it,
/// queues a `MintCiMetricsForgeToken` job. [`Observed::Unknown`] never does,
/// so a forge or store outage can't rotate the token, and neither does a
/// [`Decision::Conflict`], which the job would refuse. A kept token queues
/// only when some grant is known to be missing; that job finds the token
/// current and does not rotate it.
pub fn needs_job(seen: Observed, granted: Option<bool>) -> bool {
    match seen {
        Observed::NoForgeUser | Observed::Decided(Decision::Mint(_)) => true,
        Observed::Decided(Decision::Keep) => granted == Some(false),
        Observed::Unknown | Observed::Decided(Decision::Conflict) => false,
    }
}

impl Client {
    /// Make sure [`LOGIN`] exists, is in [`TEAM`] in every organisation, and
    /// holds a live [`TOKEN_NAME`] token in the store, minting one when it
    /// does not. The whole job of the `MintCiMetricsForgeToken` node.
    ///
    /// # Errors
    /// When the store or the forge refuses a step, when an account named
    /// [`LOGIN`] exists with another email, or when the read-back does not
    /// show the new token.
    pub async fn ensure_ci_metrics_forge_token(&self) -> Result<()> {
        let path = forge_token_path()?;
        self.ensure_ci_metrics_user().await?;
        for org in self.all_orgs().await? {
            let team = self.ensure_ci_metrics_team(&org).await?;
            self.api
                .call(|api| api.org_add_team_member(team, LOGIN).into_future())
                .await
                .with_context(|| format!("adding {LOGIN} to {org}/{TEAM}"))?;
        }

        let store = crate::store::connect()
            .await
            .context("logging in to the swarm secret store")?;
        let (stored, listed) = self.read_ci_metrics_token(&store, &path).await?;
        let reason = match classify_named(TOKEN_NAME, TOKEN_SCOPES, stored.as_ref(), &listed) {
            Decision::Keep => {
                tracing::debug!("ci metrics forge token is current; left as it is");
                return Ok(());
            }
            Decision::Conflict => bail!(
                "the forge lists more than one {TOKEN_NAME:?} token for {LOGIN:?}; delete them \
                 by id and re-run"
            ),
            Decision::Mint(reason) => reason,
        };
        let credential = self
            .replace_token(&store, LOGIN, TOKEN_NAME, TOKEN_SCOPES, &listed, &path)
            .await?;

        Forgejo::new(Auth::Token(&credential.value), self.url.clone())
            .context("building a forge client with the new token")?
            .repo_search(RepoSearchQuery::default())
            .await
            .with_context(|| format!("using {LOGIN}'s new forge token"))?;
        let (stored, listed) = self.read_ci_metrics_token(&store, &path).await?;
        let now = classify_named(TOKEN_NAME, TOKEN_SCOPES, stored.as_ref(), &listed);
        if now != Decision::Keep {
            bail!("{LOGIN}'s new forge token does not read back as current: {now:?}");
        }
        tracing::info!(?reason, %path, "ci metrics forge token minted and stored");
        Ok(())
    }

    /// The stored token at `path` and every token the forge lists for
    /// [`LOGIN`], which must exist.
    async fn read_ci_metrics_token(
        &self,
        store: &swarm_secret_client::SecretStore,
        path: &str,
    ) -> Result<(
        Option<forge::Credential>,
        Vec<forgejo_api::structs::AccessToken>,
    )> {
        let stored = store
            .read_optional(path)
            .await
            .with_context(|| format!("reading {path}"))?;
        let Some(listed) = self.list_agent_tokens(LOGIN).await? else {
            bail!("the forge has no user {LOGIN:?} after this job created it");
        };
        Ok((stored, listed))
    }

    /// Create [`LOGIN`] if there is none, refuse one with another email, and
    /// lock it out of creating repos.
    async fn ensure_ci_metrics_user(&self) -> Result<()> {
        self.create_user(LOGIN, EMAIL).await?;
        let user = self
            .api
            .call(|api| api.user_get(LOGIN).into_future())
            .await
            .with_context(|| format!("read forge user {LOGIN}"))?;
        if user.email.as_deref() != Some(EMAIL) {
            bail!(
                "forge account `{LOGIN}` exists but is not the CI metrics poller's (email {:?}, \
                 expected `{EMAIL}`); refusing to give it read on every organisation's runs",
                user.email
            );
        }
        self.api
            .call(|api| {
                api.admin_edit_user(LOGIN, super::repo_creation_lockdown(LOGIN))
                    .into_future()
            })
            .await
            .with_context(|| format!("disable repo creation for forge user {LOGIN}"))?;
        Ok(())
    }

    /// Every organisation on the forge, by name.
    async fn all_orgs(&self) -> Result<Vec<String>> {
        let mut names = Vec::new();
        let mut page = 1;
        loop {
            let (_, orgs) = self
                .api
                .call(|api| {
                    api.admin_get_all_orgs()
                        .page(page)
                        .page_size(ORG_PAGE)
                        .into_future()
                })
                .await
                .context("listing the forge's organisations")?;
            let last = orgs.len() < ORG_PAGE as usize;
            names.extend(orgs.into_iter().filter_map(|o| o.username.or(o.name)));
            if last {
                return Ok(names);
            }
            page += 1;
        }
    }

    /// The id of `org`'s [`TEAM`], created or put back to its settings.
    async fn ensure_ci_metrics_team(&self, org: &str) -> Result<i64> {
        match self.observe_ci_metrics_team(org).await {
            TeamSeen::Matches(id) => Ok(id),
            TeamSeen::Drifted(id) => {
                self.api
                    .call(|api| {
                        api.org_edit_team(
                            id,
                            EditTeamOption {
                                can_create_org_repo: Some(false),
                                description: Some(TEAM_DESCRIPTION.to_owned()),
                                includes_all_repositories: Some(true),
                                name: TEAM.to_owned(),
                                permission: Some(EditTeamOptionPermission::Read),
                                units: Some(TEAM_UNITS.map(str::to_owned).to_vec()),
                                units_map: None,
                            },
                        )
                        .into_future()
                    })
                    .await
                    .with_context(|| format!("reconcile {org}/{TEAM} team settings"))?;
                tracing::info!("swarm forge: reconciled {org}/{TEAM} team settings");
                Ok(id)
            }
            TeamSeen::Absent => self.create_ci_metrics_team(org).await,
            TeamSeen::Unknown => bail!("could not read the teams of {org}"),
        }
    }

    async fn create_ci_metrics_team(&self, org: &str) -> Result<i64> {
        let team = CreateTeamOption {
            can_create_org_repo: Some(false),
            description: Some(TEAM_DESCRIPTION.to_owned()),
            includes_all_repositories: Some(true),
            name: TEAM.to_owned(),
            permission: Some(CreateTeamOptionPermission::Read),
            units: Some(TEAM_UNITS.map(str::to_owned).to_vec()),
            units_map: None,
        };
        match self
            .api
            .call(|api| api.org_create_team(org, team.clone()).into_future())
            .await
        {
            Ok(created) => {
                tracing::info!("swarm forge: created {org}/{TEAM} team");
                created
                    .id
                    .with_context(|| format!("the forge created {org}/{TEAM} but returned no id"))
            }
            // A duplicate is a 409 or a 422; either counts once a re-read
            // finds the team, which also supplies its id.
            Err(e) => match self.observe_ci_metrics_team(org).await {
                TeamSeen::Matches(id) | TeamSeen::Drifted(id) if folds_into_success(&e, true) => {
                    Ok(id)
                }
                _ => Err(e).with_context(|| format!("create team {org}/{TEAM}")),
            },
        }
    }

    async fn observe_ci_metrics_team(&self, org: &str) -> TeamSeen {
        match self
            .api
            .call(|api| api.org_list_teams(org).into_future())
            .await
        {
            Ok((_, teams)) => teams
                .into_iter()
                .find(|t| t.name.as_deref() == Some(TEAM))
                .map_or(TeamSeen::Absent, |t| match t.id {
                    Some(id) if team_matches(&t) => TeamSeen::Matches(id),
                    Some(id) => TeamSeen::Drifted(id),
                    None => TeamSeen::Unknown,
                }),
            Err(e) => {
                tracing::warn!(error = %e, "ci metrics forge token: reading the teams of {org} failed");
                TeamSeen::Unknown
            }
        }
    }

    /// Whether every organisation's [`TEAM`] is as the job leaves it, with
    /// the account in it; `None` when a read failed.
    async fn observe_ci_metrics_grants(&self) -> Option<bool> {
        let orgs = match self.all_orgs().await {
            Ok(orgs) => orgs,
            Err(e) => {
                tracing::warn!(error = %format!("{e:#}"), "ci metrics forge token: organisation read failed");
                return None;
            }
        };
        for org in orgs {
            let id = match self.observe_ci_metrics_team(&org).await {
                TeamSeen::Matches(id) => id,
                TeamSeen::Drifted(_) | TeamSeen::Absent => return Some(false),
                TeamSeen::Unknown => return None,
            };
            match self
                .api
                .call(|api| api.org_list_team_member(id, LOGIN).into_future())
                .await
            {
                Ok(_) => {}
                Err(e) if is_not_found(&e) => return Some(false),
                Err(e) => {
                    tracing::warn!(error = %e, "ci metrics forge token: team membership read failed");
                    return None;
                }
            }
        }
        Some(true)
    }

    /// What the store and the forge say about the account's token, and
    /// whether its grants are all in place.
    async fn observe_ci_metrics(&self) -> Result<(Observed, Option<bool>)> {
        let path = forge_token_path()?;
        let store = crate::store::connect()
            .await
            .context("logging in to the swarm secret store")?;
        let stored = match store.read_optional::<forge::Credential>(&path).await {
            Ok(stored) => stored,
            Err(e) => {
                tracing::warn!(error = %e, "ci metrics forge token: store read failed");
                return Ok((Observed::Unknown, None));
            }
        };
        let seen = match self.list_agent_tokens(LOGIN).await {
            Ok(Some(listed)) => Observed::Decided(classify_named(
                TOKEN_NAME,
                TOKEN_SCOPES,
                stored.as_ref(),
                &listed,
            )),
            Ok(None) => Observed::NoForgeUser,
            Err(e) => {
                tracing::warn!(error = %format!("{e:#}"), "ci metrics forge token: forge read failed");
                Observed::Unknown
            }
        };
        Ok((seen, self.observe_ci_metrics_grants().await))
    }
}

/// Check the account now and every [`RECONCILE_INTERVAL`] after, and call
/// `enqueue`, which inserts a `MintCiMetricsForgeToken` node, when it needs a
/// job. A pass that fails is logged and retried on the next tick.
pub fn spawn(client: Arc<Client>, enqueue: impl Fn() + Send + 'static) {
    tokio::spawn(async move {
        let mut ticker = tokio::time::interval(RECONCILE_INTERVAL);
        loop {
            ticker.tick().await;
            let Some(outcome) =
                super::within_forge_deadline("ci metrics forge token", client.observe_ci_metrics())
                    .await
            else {
                continue;
            };
            match outcome {
                Ok((seen, granted)) if needs_job(seen, granted) => {
                    tracing::info!(?seen, ?granted, "ci metrics forge token: queueing a job");
                    enqueue();
                }
                Ok((seen, granted)) => {
                    tracing::debug!(?seen, ?granted, "ci metrics forge token: no job");
                }
                Err(e) => tracing::warn!(
                    error = %format!("{e:#}"),
                    retry_in_s = RECONCILE_INTERVAL.as_secs(),
                    "ci metrics forge token: pass failed; retrying next tick"
                ),
            }
        }
    });
}

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

    #[test]
    fn the_token_reads_repositories_and_nothing_else() {
        assert_eq!(TOKEN_SCOPES, "read:repository");
        assert_ne!(TOKEN_NAME, super::super::agent_token::AGENT_TOKEN_NAME);
        assert_ne!(TOKEN_NAME, super::super::hive_token::HIVE_TOKEN_NAME);
        assert_ne!(TOKEN_NAME, super::super::classifier_account::TOKEN_NAME);
        assert_ne!(TOKEN_NAME, super::super::builder_account::TOKEN_NAME);
    }

    #[test]
    fn a_mint_a_missing_account_or_a_missing_grant_queues() {
        let mint = Observed::Decided(Decision::Mint(MintReason::NotStored));
        let keep = Observed::Decided(Decision::Keep);
        assert!(needs_job(Observed::NoForgeUser, None));
        assert!(needs_job(mint, Some(true)));
        assert!(needs_job(keep, Some(false)));
        assert!(!needs_job(keep, Some(true)));
        assert!(!needs_job(keep, None));
        assert!(!needs_job(
            Observed::Decided(Decision::Conflict),
            Some(false)
        ));
        assert!(!needs_job(Observed::Unknown, Some(false)));
    }

    fn team(units: &[&str], permission: TeamPermission) -> Team {
        Team {
            can_create_org_repo: Some(false),
            description: Some(TEAM_DESCRIPTION.to_owned()),
            id: Some(7),
            includes_all_repositories: Some(true),
            name: Some(TEAM.to_owned()),
            organization: None,
            permission: Some(permission),
            units: Some(units.iter().map(|u| (*u).to_owned()).collect()),
            units_map: None,
        }
    }

    #[test]
    fn the_team_reads_actions_and_nothing_else() {
        assert!(team_matches(&team(&["repo.actions"], TeamPermission::Read)));
        assert!(!team_matches(&team(
            &["repo.actions", "repo.code"],
            TeamPermission::Read
        )));
        assert!(!team_matches(&team(
            &["repo.actions"],
            TeamPermission::Write
        )));
        let mut some_repos = team(&["repo.actions"], TeamPermission::Read);
        some_repos.includes_all_repositories = Some(false);
        assert!(!team_matches(&some_repos));
    }

    #[test]
    fn the_accounts_email_is_no_agents_or_hives() {
        assert_ne!(EMAIL, super::super::agent_email(LOGIN));
        assert_ne!(EMAIL, super::super::legacy_agent_email(LOGIN));
        assert!(!LOGIN.starts_with(hive_types::RESERVED_AGENT_PREFIX));
    }

    /// An existing account named like the poller with an agent's email is
    /// refused before the lockdown, so it never joins a team.
    #[tokio::test]
    async fn the_job_refuses_an_account_that_is_not_the_pollers() {
        use super::super::tests::{lockdown_patch, stub_forge};

        let (client, seen) = stub_forge(
            (409, r#"{"message":"user already exists"}"#),
            (200, r#"{"email":"ci-metrics@hyperhive.local"}"#),
            (200, "{}"),
        )
        .await;
        let err = client
            .ensure_ci_metrics_user()
            .await
            .expect_err("an agent's account is not the poller's");
        assert!(format!("{err:#}").contains("not the CI metrics poller's"));
        assert!(lockdown_patch(&seen, LOGIN).is_none());
    }
}