codoseo-web 0.1.0-rc.1

//! The agent API's one service layer. The REST routes (`/api/v1`) and the cloud MCP tools both
//! call these methods, so they return the same JSON ([`codoseo_mcp::cloud::types`]) and charge
//! the same daily quota.
//!
//! Every keyed method takes the already-authenticated [`ApiCaller`], counts one call against
//! the account's allowance first (a refused call counts nothing), and only then looks at its
//! arguments. Arguments arrive as the strings a caller sent (ids, check slugs, severities) and
//! are validated here, after the charge, so a malformed call costs the same as any other.
//! Another account's site is the same `NotFound` as an unknown id.

use std::collections::HashMap;

use codoseo_checks::def;
use codoseo_core::check::{CheckId, IssueBits, Severity};
use codoseo_core::plan::PlanLimits;
use codoseo_mcp::cloud::types::{
    ActiveCrawl, ChangeInfo, ChangesPage, CrawlHealth, CrawlQueued, IssueUrlsPage, PageInfo,
    PageIssue, RedirectHop, SiteHealth, SiteInfo, Usage, clip_change_text,
};
use codoseo_mcp::local::{stop_reason_code, stop_reason_words};
use codoseo_mcp::types::{FailingCheck, MAX_FAILING_CHECKS, UrlRow, rank_failing};
use codoseo_store::api_keys::{self, Charge};
use codoseo_store::crawls::{self, Crawl, CrawlStatus, ManualOutcome, ManualWindow};
use codoseo_store::explorer::{self, PageFilter};
use codoseo_store::reports;
use codoseo_store::sites::{self, Site};
use sqlx::PgPool;
use time::OffsetDateTime;
use url::Url;
use uuid::Uuid;

use super::auth::ApiCaller;
use super::error::AgentError;
use crate::crawl_policy::{limit_message, manual_priority};
use crate::state::AppState;

/// Rows a list returns when the caller doesn't say.
pub const DEFAULT_LIMIT: u32 = 50;
/// The most rows one call returns.
pub const MAX_LIMIT: u32 = 200;
/// Example URLs listed per failing check.
const EXAMPLES_PER_CHECK: i64 = 3;

/// Where the caller stands against today's allowance after a call. `None` fields mean the plan
/// has no limit (self-hosted).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Quota {
    pub limit: Option<u32>,
    pub remaining: Option<u32>,
}

/// A keyed call's result, with the quota it left behind (`None` when the charge itself failed
/// on a database error). The REST layer puts the quota in headers; MCP only needs the outcome.
#[derive(Debug)]
pub struct Reply<T> {
    pub quota: Option<Quota>,
    pub outcome: Result<T, AgentError>,
}

impl<T> Reply<T> {
    pub fn into_result(self) -> Result<T, AgentError> {
        self.outcome
    }
}

pub struct AgentService<'a> {
    state: &'a AppState,
}

impl<'a> AgentService<'a> {
    pub fn new(state: &'a AppState) -> AgentService<'a> {
        AgentService { state }
    }

    /// Counts one call, then runs `work`. `work` is a future that hasn't started: nothing in it
    /// runs when the charge is refused.
    async fn metered<T>(
        &self,
        caller: &ApiCaller,
        work: impl Future<Output = Result<T, AgentError>>,
    ) -> Reply<T> {
        let limit = PlanLimits::for_plan(caller.account.plan).api_calls_per_day;
        match api_keys::charge(&self.state.pool, caller.account.id, limit).await {
            Err(e) => Reply {
                quota: None,
                outcome: Err(e.into()),
            },
            Ok(Charge::OverQuota { limit }) => {
                // The reset comes from Postgres' clock, the one the day was counted by.
                let outcome = match api_keys::day_end(&self.state.pool, None).await {
                    Ok(end) => Err(AgentError::QuotaExceeded {
                        limit,
                        retry_after_secs: u64::try_from(end.seconds_left).unwrap_or(1),
                    }),
                    Err(e) => Err(e.into()),
                };
                Reply {
                    quota: Some(Quota {
                        limit: Some(limit),
                        remaining: Some(0),
                    }),
                    outcome,
                }
            }
            Ok(Charge::Ok { used, limit }) => Reply {
                quota: Some(Quota {
                    limit,
                    remaining: limit.map(|l| l.saturating_sub(clamp_u32(used))),
                }),
                outcome: work.await,
            },
        }
    }

    /// Counts a call that the caller's own arguments already made unanswerable (a query string
    /// that doesn't parse) and answers with `error`: every authenticated request costs one.
    pub async fn refuse<T>(&self, caller: &ApiCaller, error: AgentError) -> Reply<T> {
        self.metered(caller, async { Err(error) }).await
    }

    pub async fn list_sites(&self, caller: &ApiCaller) -> Reply<Vec<SiteInfo>> {
        self.metered(caller, self.list_sites_work(caller)).await
    }

    pub async fn site_health(&self, caller: &ApiCaller, site: &str) -> Reply<SiteHealth> {
        self.metered(caller, self.site_health_work(caller, site))
            .await
    }

    pub async fn issue_urls(
        &self,
        caller: &ApiCaller,
        site: &str,
        check: &str,
        limit: Option<u32>,
        offset: Option<u32>,
    ) -> Reply<IssueUrlsPage> {
        self.metered(
            caller,
            self.issue_urls_work(caller, site, check, limit, offset),
        )
        .await
    }

    pub async fn page(&self, caller: &ApiCaller, site: &str, url: &str) -> Reply<PageInfo> {
        self.metered(caller, self.page_work(caller, site, url))
            .await
    }

    pub async fn changes(
        &self,
        caller: &ApiCaller,
        site: &str,
        severity: Option<&str>,
        limit: Option<u32>,
        offset: Option<u32>,
    ) -> Reply<ChangesPage> {
        self.metered(
            caller,
            self.changes_work(caller, site, severity, limit, offset),
        )
        .await
    }

    /// Queues a manual crawl exactly as the Run crawl button does: the plan's allowance and
    /// lane, one crawl at a time.
    pub async fn run_crawl(&self, caller: &ApiCaller, site: &str) -> Reply<CrawlQueued> {
        self.metered(caller, self.run_crawl_work(caller, site))
            .await
    }

    /// Today's calls and the allowance. Free: it isn't counted.
    pub async fn usage(&self, caller: &ApiCaller) -> Reply<Usage> {
        let limit = PlanLimits::for_plan(caller.account.plan).api_calls_per_day;
        let pool = &self.state.pool;
        let outcome = async {
            let calls = clamp_u32(api_keys::usage_today(pool, caller.account.id).await?);
            let end = api_keys::day_end(pool, None).await?;
            Ok::<_, AgentError>(Usage {
                calls_today: calls,
                limit,
                remaining: limit.map(|l| l.saturating_sub(calls)),
                resets_at: end.resets_at,
            })
        }
        .await;
        Reply {
            quota: outcome.as_ref().ok().map(|u| Quota {
                limit: u.limit,
                remaining: u.remaining,
            }),
            outcome,
        }
    }

    /// One of the caller's sites; another account's looks exactly like an unknown id.
    async fn site(&self, caller: &ApiCaller, raw: &str) -> Result<Site, AgentError> {
        let id: Uuid = raw
            .trim()
            .parse()
            .map_err(|_| AgentError::site_not_found())?;
        sites::get_for_account(&self.state.pool, caller.account.id, id)
            .await?
            .ok_or_else(AgentError::site_not_found)
    }

    async fn list_sites_work(&self, caller: &ApiCaller) -> Result<Vec<SiteInfo>, AgentError> {
        let pool = &self.state.pool;
        let list = sites::list_for_account(pool, caller.account.id).await?;
        let latest: HashMap<Uuid, (Option<i16>, Option<OffsetDateTime>)> =
            crawls::latest_done_for_account(pool, caller.account.id)
                .await?
                .into_iter()
                .map(|(id, score, at)| (id, (score, at)))
                .collect();
        Ok(list
            .into_iter()
            .map(|s| {
                let (score, at) = latest.get(&s.id).copied().unwrap_or((None, None));
                SiteInfo {
                    id: s.id,
                    domain: s.domain,
                    start_url: s.start_url,
                    monitoring_active: s.monitoring_active,
                    schedule: s.schedule,
                    health_score: score.and_then(|n| u8::try_from(n).ok()),
                    last_crawled_at: at,
                }
            })
            .collect())
    }

    async fn site_health_work(
        &self,
        caller: &ApiCaller,
        site: &str,
    ) -> Result<SiteHealth, AgentError> {
        let pool = &self.state.pool;
        let site = self.site(caller, site).await?;
        let latest = match crawls::latest_done(pool, site.id).await? {
            Some(crawl) => Some(crawl_health(pool, &crawl).await?),
            None => None,
        };
        let active = crawls::active(pool, site.id).await?.map(|c| ActiveCrawl {
            crawl_id: c.id,
            number: c.number,
            status: if c.status == CrawlStatus::Running {
                "running"
            } else {
                "queued"
            }
            .to_owned(),
            pages_done: c.progress().map(|p| p.pages_done),
        });
        let audit_url = self
            .state
            .config
            .base_url
            .join(&format!("s/{}/audit", site.id))
            .map_or_else(|_| format!("/s/{}/audit", site.id), |u| u.to_string());
        Ok(SiteHealth {
            id: site.id,
            next_crawl_at: sites::next_crawl_at(pool, site.id).await?,
            domain: site.domain,
            start_url: site.start_url,
            monitoring_active: site.monitoring_active,
            schedule: site.schedule,
            latest_crawl: latest,
            active_crawl: active,
            audit_url,
        })
    }

    async fn issue_urls_work(
        &self,
        caller: &ApiCaller,
        site: &str,
        check: &str,
        limit: Option<u32>,
        offset: Option<u32>,
    ) -> Result<IssueUrlsPage, AgentError> {
        let pool = &self.state.pool;
        let site = self.site(caller, site).await?;
        let check = parse_check(check)?;
        let mut page = IssueUrlsPage {
            site_id: site.id,
            check,
            title: def(check).title.to_owned(),
            crawl_number: None,
            total: 0,
            limit: clamp_limit(limit),
            offset: offset.unwrap_or(0),
            urls: Vec::new(),
            next_offset: None,
        };
        let Some(crawl) = crawls::latest_done(pool, site.id).await? else {
            return Ok(page);
        };
        let rows = issue_page(pool, crawl.id, check, limit, offset).await?;
        page.crawl_number = Some(crawl.number);
        page.total = rows.total;
        page.urls = rows.urls;
        page.next_offset = rows.next_offset;
        Ok(page)
    }

    async fn page_work(
        &self,
        caller: &ApiCaller,
        site: &str,
        url: &str,
    ) -> Result<PageInfo, AgentError> {
        let pool = &self.state.pool;
        let site = self.site(caller, site).await?;
        if url.trim().is_empty() {
            return Err(AgentError::BadRequest("The url is required.".to_owned()));
        }
        let base = Url::parse(&site.start_url)
            .map_err(|e| AgentError::Internal(format!("site start url: {e}")))?;
        let url = codoseo_core::url::normalize(&base, url)
            .ok_or_else(|| AgentError::BadRequest("That is not a valid page URL.".to_owned()))?;
        let crawl = crawls::latest_done(pool, site.id).await?.ok_or_else(|| {
            AgentError::NotFound("This site has no finished crawl yet.".to_owned())
        })?;
        let page = explorer::page(pool, site.id, crawl.id, codoseo_core::url::url_hash(&url))
            .await?
            .ok_or_else(|| {
                AgentError::NotFound("That URL is not in the latest crawl of this site.".to_owned())
            })?;
        let mut issues: Vec<PageIssue> = IssueBits(page.issues)
            .iter()
            .filter_map(CheckId::from_bit)
            .map(|check| PageIssue {
                check,
                title: def(check).title.to_owned(),
                severity: def(check).severity,
            })
            .collect();
        issues.sort_by_key(|i| (i.severity, i.check));
        Ok(PageInfo {
            site_id: site.id,
            crawl_number: crawl.number,
            url: page.url,
            status: page.status,
            redirect_chain: page
                .redirect_chain
                .into_iter()
                .map(|(status, url)| RedirectHop { status, url })
                .collect(),
            redirect_target: page.redirect_target,
            response_ms: page.response_ms,
            size_bytes: page.size_bytes,
            content_type: page.content_type,
            depth: page.depth,
            in_sitemap: page.in_sitemap,
            indexability: page.indexability,
            title: page.title,
            meta_description: page.meta_description,
            meta_robots: page.meta_robots,
            x_robots_tag: page.x_robots_tag,
            canonical: page.canonical,
            h1: page.h1,
            h2: page.h2,
            word_count: page.word_count,
            inlinks: page.inlinks,
            outlinks_internal: page.outlinks_internal,
            outlinks_external: page.outlinks_external,
            issues,
        })
    }

    async fn changes_work(
        &self,
        caller: &ApiCaller,
        site: &str,
        severity: Option<&str>,
        limit: Option<u32>,
        offset: Option<u32>,
    ) -> Result<ChangesPage, AgentError> {
        let pool = &self.state.pool;
        let site = self.site(caller, site).await?;
        let severity = severity
            .map(str::trim)
            .filter(|s| !s.is_empty())
            .map(parse_severity)
            .transpose()?;
        let (limit, offset) = (clamp_limit(limit), offset.unwrap_or(0));
        let mut out = ChangesPage {
            site_id: site.id,
            crawl_number: None,
            crawl_finished_at: None,
            total: 0,
            limit,
            offset,
            changes: Vec::new(),
            next_offset: None,
        };
        let Some(crawl) = crawls::latest_done(pool, site.id).await? else {
            return Ok(out);
        };
        let counts = reports::change_kind_counts(pool, crawl.id).await?;
        let rows = reports::changes_for_crawl_at(
            pool,
            crawl.id,
            severity,
            i64::from(offset),
            i64::from(limit),
        )
        .await?;
        out.crawl_number = Some(crawl.number);
        out.crawl_finished_at = crawl.finished_at;
        out.total = clamp_u32(severity.map_or_else(|| counts.total(), |s| counts.severity(s)));
        let shown = u32::try_from(rows.len()).unwrap_or(u32::MAX);
        out.changes = rows
            .into_iter()
            .map(|c| ChangeInfo {
                kind: c.kind,
                severity: c.severity,
                url: c.url,
                before: clip_change_text(&c.before),
                after: clip_change_text(&c.after),
            })
            .collect();
        out.next_offset = next_offset(offset, shown, out.total);
        Ok(out)
    }

    async fn run_crawl_work(
        &self,
        caller: &ApiCaller,
        site: &str,
    ) -> Result<CrawlQueued, AgentError> {
        let site = self.site(caller, site).await?;
        let plan = caller.account.plan;
        let allowance = PlanLimits::for_plan(plan).manual_crawls;
        let outcome = crawls::enqueue_manual_checked(
            &self.state.pool,
            site.id,
            &site.domain,
            manual_priority(plan),
            ManualWindow::for_allowance(allowance),
        )
        .await
        // The site was deleted between the lookup and the insert.
        .map_err(|e| match e {
            sqlx::Error::RowNotFound => AgentError::site_not_found(),
            e => e.into(),
        })?;
        match outcome {
            ManualOutcome::Queued { id, number } => Ok(CrawlQueued {
                site_id: site.id,
                crawl_id: id,
                number,
                status: "queued".to_owned(),
            }),
            ManualOutcome::Busy(status) => {
                let what = if status == CrawlStatus::Running {
                    "running"
                } else {
                    "queued"
                };
                Err(AgentError::CrawlInProgress(format!(
                    "A crawl is already {what} for this site."
                )))
            }
            ManualOutcome::LimitReached { frees_at } => Err(AgentError::PlanLimit(limit_message(
                plan,
                allowance,
                frees_at - OffsetDateTime::now_utc(),
            ))),
        }
    }
}

/// How many rows a list call returns: `limit` if given, at most [`MAX_LIMIT`], at least 1.
pub fn clamp_limit(limit: Option<u32>) -> u32 {
    limit.unwrap_or(DEFAULT_LIMIT).clamp(1, MAX_LIMIT)
}

/// The offset of the next page, when rows remain after `offset + shown`.
fn next_offset(offset: u32, shown: u32, total: u32) -> Option<u32> {
    offset.checked_add(shown).filter(|next| *next < total)
}

/// A check by slug.
pub fn parse_check(slug: &str) -> Result<CheckId, AgentError> {
    CheckId::from_slug(slug.trim()).ok_or_else(|| {
        let valid: Vec<&str> = CheckId::ALL.iter().map(|c| c.slug()).collect();
        AgentError::BadRequest(format!(
            "Unknown check \"{slug}\". The check slugs are: {}.",
            valid.join(", ")
        ))
    })
}

fn clamp_u32(n: i64) -> u32 {
    u32::try_from(n.max(0)).unwrap_or(u32::MAX)
}

/// `critical`, `warning` or `notice` (lowercase, as the web app's filters write them).
pub fn parse_severity(s: &str) -> Result<Severity, AgentError> {
    Severity::from_slug(s.trim()).ok_or_else(|| {
        AgentError::BadRequest(format!(
            "Unknown severity \"{s}\". Use critical, warning or notice."
        ))
    })
}

/// A finished crawl's score, counts and failing checks (most severe first, with example URLs
/// fetched in one query). It reads the crawl only, so it serves any crawl id the caller is
/// already allowed to see, a site's or a quick audit's.
pub async fn crawl_health(pool: &PgPool, crawl: &Crawl) -> Result<CrawlHealth, AgentError> {
    let summary = crawl.summary();
    let mut failing = rank_failing(
        summary
            .iter()
            .flat_map(|s| s.counts.iter())
            .filter_map(|(slug, n)| Some((CheckId::from_slug(slug)?, *n))),
    );
    let more = failing.len().saturating_sub(MAX_FAILING_CHECKS);
    failing.truncate(MAX_FAILING_CHECKS);
    let ids: Vec<CheckId> = failing.iter().map(|&(id, _)| id).collect();
    let mut examples = explorer::example_urls(pool, crawl.id, &ids, EXAMPLES_PER_CHECK).await?;
    let failing_checks = failing
        .into_iter()
        .map(|(check, count)| {
            let d = def(check);
            FailingCheck {
                check,
                title: d.title.to_owned(),
                severity: d.severity,
                count,
                example_urls: examples
                    .remove(&check)
                    .unwrap_or_default()
                    .iter()
                    .filter_map(|u| Url::parse(u).ok())
                    .collect(),
            }
        })
        .collect();
    Ok(CrawlHealth {
        crawl_id: crawl.id,
        number: crawl.number,
        finished_at: crawl.finished_at,
        health_score: crawl.health_score.and_then(|n| u8::try_from(n).ok()),
        checks_passed: crawl.checks_passed.and_then(|n| u16::try_from(n).ok()),
        checks_total: crawl.checks_total.and_then(|n| u16::try_from(n).ok()),
        pages_crawled: summary.as_ref().map_or(0, |s| s.report_summary.pages),
        stop_reason: summary.as_ref().map_or_else(
            || "unknown".to_owned(),
            |s| stop_reason_words(&s.stop_reason),
        ),
        stop_code: summary
            .as_ref()
            .map_or("unknown", |s| stop_reason_code(&s.stop_reason))
            .to_owned(),
        failing_checks,
        more_failing_checks: u16::try_from(more).unwrap_or(u16::MAX),
    })
}

/// One page of the pages of a crawl that fail `check`.
#[derive(Debug, Clone, PartialEq)]
pub struct IssueRows {
    /// Pages failing the check in the crawl.
    pub total: u32,
    pub limit: u32,
    pub offset: u32,
    pub urls: Vec<UrlRow>,
    /// Pass as `offset` for the next page; none on the last page.
    pub next_offset: Option<u32>,
}

/// The pages of `crawl_id` that fail `check`, `limit` (clamped) from `offset`, in crawl order.
pub async fn issue_page(
    pool: &PgPool,
    crawl_id: Uuid,
    check: CheckId,
    limit: Option<u32>,
    offset: Option<u32>,
) -> Result<IssueRows, AgentError> {
    let (limit, offset) = (clamp_limit(limit), offset.unwrap_or(0));
    let filter = PageFilter::Check(check);
    let (matching, _) = explorer::match_count(pool, crawl_id, filter, "").await?;
    let rows =
        explorer::rows_at(pool, crawl_id, filter, i64::from(offset), i64::from(limit)).await?;
    let total = clamp_u32(matching);
    let shown = u32::try_from(rows.len()).unwrap_or(u32::MAX);
    let urls = rows
        .into_iter()
        .filter_map(|r| {
            Some(UrlRow {
                url: Url::parse(&r.url).ok()?,
                status: r.status,
                title: r.title,
                indexability: r.indexability,
            })
        })
        .collect();
    Ok(IssueRows {
        total,
        limit,
        offset,
        urls,
        next_offset: next_offset(offset, shown, total),
    })
}

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

    #[test]
    fn limits_are_clamped() {
        assert_eq!(clamp_limit(None), 50);
        assert_eq!(clamp_limit(Some(0)), 1);
        assert_eq!(clamp_limit(Some(10_000)), 200);
    }

    #[test]
    fn severities_are_lowercase_slugs() {
        assert_eq!(parse_severity("critical").unwrap(), Severity::Critical);
        assert_eq!(parse_severity(" notice ").unwrap(), Severity::Notice);
        assert!(parse_severity("Critical").is_err());
        assert!(parse_severity("severe").is_err());
    }

    #[test]
    fn the_next_page_starts_where_this_one_ends_until_the_total_is_reached() {
        assert_eq!(next_offset(0, 50, 120), Some(50));
        assert_eq!(next_offset(100, 20, 120), None);
        assert_eq!(next_offset(0, 0, 0), None);
        assert_eq!(next_offset(u32::MAX, 5, u32::MAX), None);
    }
}