//! Gitea activity feed ingestion.
//!
//! Hits `/api/v1/users/{user}/activities/feeds?only-performed-by=true`
//! which returns events the user themselves caused (not received events
//! from others they follow). No ETag support upstream, so each tick fetches
//! page 1 and relies on idempotent upsert. First run paginates further to
//! seed history.
//!
//! Each item carries a self-contained payload — including the event-emitting
//! host — so the reshape layer can construct URLs without needing config.

use std::collections::HashSet;
use std::sync::Arc;

use async_trait::async_trait;
use chrono::{DateTime, Utc};
use moments_core::{EventSource, EventWriter, PollerStateStore, SourceError};
use moments_entities::{Event, RepoLanguage, Source};
use reqwest::{Client, header};
use serde_json::Value;
use tracing::debug;

const SOURCE_NAME: &str = "gitea";
const USER_AGENT: &str = concat!(
    "moments/",
    env!("CARGO_PKG_VERSION"),
    " (+https://rob.tn)"
);
const MAX_BACKFILL_PAGES: u32 = 20;

#[derive(Clone, Debug)]
pub struct GiteaConfig {
    /// e.g. `git.lair.cafe`. Used to construct URLs the API doesn't return
    /// directly (issue / PR / commit web links) and stamped into each event
    /// payload for the reshape layer.
    pub host: String,
    pub user: String,
    pub token: Option<String>,
    pub per_page: u32,
}

impl Default for GiteaConfig {
    fn default() -> Self {
        Self {
            host: "git.lair.cafe".into(),
            user: "grenade".into(),
            token: None,
            per_page: 50,
        }
    }
}

pub struct GiteaSource {
    client: Client,
    writer: Arc<dyn EventWriter>,
    state: Arc<dyn PollerStateStore>,
    config: GiteaConfig,
}

impl GiteaSource {
    pub fn new(
        client: Client,
        writer: Arc<dyn EventWriter>,
        state: Arc<dyn PollerStateStore>,
        config: GiteaConfig,
    ) -> Self {
        Self {
            client,
            writer,
            state,
            config,
        }
    }

    fn user_feed_base_url(&self) -> String {
        format!(
            "https://{}/api/v1/users/{}/activities/feeds?only-performed-by=true&limit={}",
            self.config.host, self.config.user, self.config.per_page
        )
    }

    fn org_feed_base_url(&self, org: &str) -> String {
        format!(
            "https://{}/api/v1/orgs/{}/activities/feeds?limit={}",
            self.config.host, org, self.config.per_page
        )
    }

    fn apply_headers(&self, mut req: reqwest::RequestBuilder) -> reqwest::RequestBuilder {
        req = req
            .header(header::ACCEPT, "application/json")
            .header(header::USER_AGENT, USER_AGENT);
        if let Some(token) = &self.config.token {
            req = req.header(header::AUTHORIZATION, format!("token {token}"));
        }
        req
    }

    /// Discover organizations the authenticated user belongs to.
    /// Returns an empty vec if no token is configured or the request fails.
    async fn discover_orgs(&self) -> Result<Vec<String>, SourceError> {
        if self.config.token.is_none() {
            return Ok(vec![]);
        }
        let url = format!("https://{}/api/v1/user/orgs", self.config.host);
        let req = self.apply_headers(self.client.get(&url));
        let resp = req
            .send()
            .await
            .map_err(|e| SourceError::Http(e.to_string()))?;
        if !resp.status().is_success() {
            tracing::warn!(status = %resp.status(), "failed to discover gitea orgs");
            return Ok(vec![]);
        }
        let orgs: Vec<Value> = resp
            .json()
            .await
            .map_err(|e| SourceError::Parse(e.to_string()))?;
        Ok(orgs
            .iter()
            .filter_map(|o| o.get("username").and_then(Value::as_str).map(String::from))
            .collect())
    }

    /// Poll a single activity feed, paginating on first run. When `filter_user`
    /// is true, only events performed by `self.config.user` are ingested (used
    /// for org feeds which contain all members' activity).
    ///
    /// `base_url` should contain everything except the `&page=N` suffix.
    /// Returns (ingested_count, set_of_repo_full_names).
    async fn poll_feed(
        &self,
        state_key: &str,
        base_url: &str,
        filter_user: bool,
    ) -> Result<(usize, HashSet<String>), SourceError> {
        let prior = self.state.load(state_key).await?;
        let first_run = prior.is_none();
        let max_pages = if first_run { MAX_BACKFILL_PAGES } else { 1 };

        let mut total = 0usize;
        let mut repos = HashSet::new();
        for page in 1..=max_pages {
            let url = format!("{base_url}&page={page}");
            let req = self.apply_headers(self.client.get(&url));
            let resp = req
                .send()
                .await
                .map_err(|e| SourceError::Http(e.to_string()))?;
            if !resp.status().is_success() {
                return Err(SourceError::Http(format!("{} GET {}", resp.status(), url)));
            }
            let items: Vec<Value> = resp
                .json()
                .await
                .map_err(|e| SourceError::Parse(e.to_string()))?;
            if items.is_empty() {
                break;
            }

            // Collect repo names from feed items
            for item in &items {
                if let Some(name) = item
                    .get("repo")
                    .and_then(|r| r.get("full_name"))
                    .and_then(Value::as_str)
                {
                    repos.insert(name.to_string());
                }
            }

            let events: Vec<Event> = items
                .iter()
                .filter(|it| {
                    if !filter_user {
                        return true;
                    }
                    it.get("act_user")
                        .and_then(|u| u.get("login"))
                        .and_then(Value::as_str)
                        .map(|login| login.eq_ignore_ascii_case(&self.config.user))
                        .unwrap_or(false)
                })
                .filter_map(|it| parse_gitea_event(it, &self.config.host))
                .collect();
            total += self.writer.upsert_events(&events).await?;

            if items.len() < self.config.per_page as usize {
                break;
            }
        }

        self.state.touch(state_key).await?;
        Ok((total, repos))
    }

    /// Fetch language breakdowns for the given repos via the Gitea REST API.
    async fn fetch_languages(&self, repos: &HashSet<String>) -> Result<usize, SourceError> {
        let mut total = 0usize;
        for repo in repos {
            let url = format!(
                "https://{}/api/v1/repos/{}/languages",
                self.config.host, repo
            );
            let req = self.apply_headers(self.client.get(&url));
            let resp = req
                .send()
                .await
                .map_err(|e| SourceError::Http(e.to_string()))?;
            if !resp.status().is_success() {
                tracing::warn!(repo = %repo, status = %resp.status(), "gitea language fetch failed; skipping");
                continue;
            }
            let lang_map: std::collections::HashMap<String, i64> = resp
                .json()
                .await
                .map_err(|e| SourceError::Parse(e.to_string()))?;

            let languages: Vec<RepoLanguage> = lang_map
                .into_iter()
                .map(|(language, bytes)| RepoLanguage {
                    source: Source::Gitea,
                    repo: repo.clone(),
                    language,
                    bytes,
                    color: None, // Gitea doesn't return colors
                })
                .collect();
            total += self.writer.upsert_repo_languages(&languages).await?;
        }
        debug!(total, repos = repos.len(), "gitea repo languages updated");
        Ok(total)
    }
}

#[async_trait]
impl EventSource for GiteaSource {
    fn name(&self) -> &'static str {
        SOURCE_NAME
    }

    async fn poll(&self) -> Result<usize, SourceError> {
        let mut all_repos = HashSet::new();

        // Poll user's own activity feed (existing behavior).
        let user_url = self.user_feed_base_url();
        let (mut total, repos) = self.poll_feed(SOURCE_NAME, &user_url, false).await?;
        all_repos.extend(repos);

        // Discover orgs and poll each org's activity feed, filtering for
        // events performed by this user.
        let orgs = self.discover_orgs().await?;
        for org in &orgs {
            let state_key = format!("gitea:org:{org}");
            let org_url = self.org_feed_base_url(org);
            match self.poll_feed(&state_key, &org_url, true).await {
                Ok((n, repos)) => {
                    total += n;
                    all_repos.extend(repos);
                }
                Err(e) => {
                    tracing::warn!(org = %org, error = %e, "failed to poll org feed");
                }
            }
        }

        if let Err(e) = self.fetch_languages(&all_repos).await {
            tracing::warn!(error = %e, "gitea language fetch failed; continuing");
        }

        debug!(ingested = total, orgs = orgs.len(), "gitea poll complete");
        Ok(total)
    }
}

/// Convert a Gitea activity feed item into our Event row. The host gets
/// stamped into the payload as `_host` so the reshape layer can build
/// web URLs without needing global config.
fn parse_gitea_event(item: &Value, host: &str) -> Option<Event> {
    let id = item.get("id").and_then(Value::as_i64)?;
    let op_type = item.get("op_type").and_then(Value::as_str)?.to_string();
    let created_str = item.get("created").and_then(Value::as_str)?;
    let occurred_at = DateTime::parse_from_rfc3339(created_str)
        .ok()?
        .with_timezone(&Utc);
    let private = item.get("is_private").and_then(Value::as_bool).unwrap_or(false);

    let mut payload = item.clone();
    if let Some(obj) = payload.as_object_mut() {
        obj.insert("_host".into(), Value::String(host.into()));
    }

    Some(Event {
        id: format!("gitea:{id}"),
        source: Source::Gitea,
        action: op_type,
        occurred_at,
        public: !private,
        payload,
    })
}

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

    #[test]
    fn parse_commit_repo() {
        let raw = json!({
            "id": 973,
            "op_type": "commit_repo",
            "ref_name": "refs/heads/main",
            "is_private": false,
            "content": "{\"Commits\":[{\"Sha1\":\"abc123\"}],\"Len\":1}",
            "created": "2026-05-03T16:37:45Z",
            "repo": { "full_name": "grenade/moments" }
        });
        let ev = parse_gitea_event(&raw, "git.lair.cafe").expect("parses");
        assert_eq!(ev.id, "gitea:973");
        assert_eq!(ev.source, Source::Gitea);
        assert_eq!(ev.action, "commit_repo");
        assert!(ev.public);
        // host stamped into payload
        assert_eq!(
            ev.payload.get("_host").and_then(|v| v.as_str()),
            Some("git.lair.cafe")
        );
    }

    #[test]
    fn org_event_user_filter_predicate() {
        let by_user = json!({
            "id": 500, "op_type": "commit_repo", "is_private": false,
            "created": "2026-05-03T10:00:00Z",
            "act_user": { "login": "grenade" },
            "repo": { "full_name": "myorg/somerepo" }
        });
        let by_other = json!({
            "id": 501, "op_type": "commit_repo", "is_private": false,
            "created": "2026-05-03T10:01:00Z",
            "act_user": { "login": "otherperson" },
            "repo": { "full_name": "myorg/somerepo" }
        });
        // Both parse as valid events
        assert!(parse_gitea_event(&by_user, "git.lair.cafe").is_some());
        assert!(parse_gitea_event(&by_other, "git.lair.cafe").is_some());
        // The user-filter predicate used by poll_feed
        let is_user = |item: &Value, user: &str| -> bool {
            item.get("act_user")
                .and_then(|u| u.get("login"))
                .and_then(Value::as_str)
                .map(|login| login.eq_ignore_ascii_case(user))
                .unwrap_or(false)
        };
        assert!(is_user(&by_user, "grenade"));
        assert!(!is_user(&by_other, "grenade"));
        // Case-insensitive match
        assert!(is_user(&by_user, "Grenade"));
    }

    #[test]
    fn private_event_marked_private() {
        let raw = json!({
            "id": 100,
            "op_type": "commit_repo",
            "is_private": true,
            "created": "2026-05-03T00:00:00Z",
            "repo": { "full_name": "grenade/private" }
        });
        let ev = parse_gitea_event(&raw, "git.lair.cafe").expect("parses");
        assert!(!ev.public);
    }
}