//! Fill-proposal validator (Phase 43 v2 — real consistency checks).
//!
//! PRD checks:
//!   - Schema compliance (propose_done shape: `{fills: [{candidate_id, name}]}`)
//!   - Completeness (endorsed count == target_count)
//!   - Worker existence (every candidate_id present in workers roster)
//!   - Status check (worker.status == "active")
//!   - Client blacklist (worker NOT in client.blacklisted_clients)
//!   - Geo/role match (worker city/state/role matches contract)
//!
//! The contract metadata (target_count, city, state, role, client_id)
//! travels alongside the JSON payload under a `_context` key:
//! `{"_context": {"target_count": 2, "city": "Toledo", "state": "OH",
//!   "role": "Welder", "client_id": "CLI-00099"}, "fills": [...]}`.
//! This keeps the Validator trait signature stable while letting the
//! validator cross-check fills against contract truth.
//!
//! Worker-existence + status + geo + blacklist all share a single
//! lookup trait (`WorkerLookup`) so the validator stays decoupled
//! from queryd / parquet / catalogd transport details.

use crate::{
    Artifact, Report, Validator, ValidationError, WorkerLookup, WorkerRecord,
};
use std::sync::Arc;
use std::time::Instant;

pub struct FillValidator {
    workers: Arc<dyn WorkerLookup>,
}

impl FillValidator {
    pub fn new(workers: Arc<dyn WorkerLookup>) -> Self {
        Self { workers }
    }
}

#[derive(Debug, Default)]
struct FillContext {
    target_count: Option<usize>,
    city: Option<String>,
    state: Option<String>,
    role: Option<String>,
    client_id: Option<String>,
}

fn extract_context(value: &serde_json::Value) -> FillContext {
    let ctx_obj = value.get("_context").and_then(|c| c.as_object());
    let ctx = match ctx_obj {
        Some(o) => o,
        None => return FillContext::default(),
    };
    FillContext {
        target_count: ctx.get("target_count").and_then(|v| v.as_u64()).map(|n| n as usize),
        city: ctx.get("city").and_then(|v| v.as_str()).map(String::from),
        state: ctx.get("state").and_then(|v| v.as_str()).map(String::from),
        role: ctx.get("role").and_then(|v| v.as_str()).map(String::from),
        client_id: ctx.get("client_id").and_then(|v| v.as_str()).map(String::from),
    }
}

fn eq_ci(a: &str, b: &str) -> bool {
    a.trim().eq_ignore_ascii_case(b.trim())
}

impl Validator for FillValidator {
    fn name(&self) -> &'static str { "staffing.fill" }

    fn validate(&self, artifact: &Artifact) -> Result<Report, ValidationError> {
        let started = Instant::now();
        let value = match artifact {
            Artifact::FillProposal(v) => v,
            other => return Err(ValidationError::Schema {
                field: "artifact".into(),
                reason: format!("FillValidator expects FillProposal, got {other:?}"),
            }),
        };

        // ── Schema check ──
        let fills = value.get("fills").and_then(|f| f.as_array()).ok_or(
            ValidationError::Schema {
                field: "fills".into(),
                reason: "expected top-level `fills` array".into(),
            },
        )?;
        for (i, fill) in fills.iter().enumerate() {
            if fill.get("candidate_id").is_none() {
                return Err(ValidationError::Schema {
                    field: format!("fills[{i}].candidate_id"),
                    reason: "missing".into(),
                });
            }
            if fill.get("name").is_none() {
                return Err(ValidationError::Schema {
                    field: format!("fills[{i}].name"),
                    reason: "missing".into(),
                });
            }
        }

        let ctx = extract_context(value);

        // ── Completeness: count match ──
        if let Some(target) = ctx.target_count {
            if fills.len() != target {
                return Err(ValidationError::Completeness {
                    reason: format!(
                        "endorsed count {} != target_count {target}",
                        fills.len()
                    ),
                });
            }
        }

        // ── Cross-roster checks ──
        let mut findings: Vec<crate::Finding> = vec![];
        let mut seen_ids = std::collections::HashSet::new();
        for (i, fill) in fills.iter().enumerate() {
            let candidate_id = fill.get("candidate_id").and_then(|v| v.as_str()).unwrap_or("");
            let proposed_name = fill.get("name").and_then(|v| v.as_str()).unwrap_or("");

            // Duplicate-ID guard inside one fill.
            if !seen_ids.insert(candidate_id.to_string()) {
                return Err(ValidationError::Consistency {
                    reason: format!(
                        "duplicate candidate_id {candidate_id:?} appears multiple times in fills"
                    ),
                });
            }

            // Worker existence — the gate that catches phantom IDs the
            // model fabricates. This is the load-bearing check for
            // the 0→85% pattern.
            let worker: WorkerRecord = match self.workers.find(candidate_id) {
                Some(w) => w,
                None => return Err(ValidationError::Consistency {
                    reason: format!(
                        "fills[{i}].candidate_id {candidate_id:?} does not exist in worker roster"
                    ),
                }),
            };

            // Status — only "active" workers can be endorsed.
            if !eq_ci(&worker.status, "active") {
                return Err(ValidationError::Consistency {
                    reason: format!(
                        "fills[{i}] worker {candidate_id:?} has status {:?}, expected \"active\"",
                        worker.status
                    ),
                });
            }

            // Client blacklist.
            if let Some(client) = ctx.client_id.as_deref() {
                if worker.blacklisted_clients.iter().any(|b| eq_ci(b, client)) {
                    return Err(ValidationError::Policy {
                        reason: format!(
                            "fills[{i}] worker {candidate_id:?} blacklisted for client {client:?}"
                        ),
                    });
                }
            }

            // Geo / role match — warn-level when missing context, hard
            // fail on mismatch with explicit contract values.
            if let (Some(want_city), Some(have_city)) = (ctx.city.as_deref(), worker.city.as_deref()) {
                if !eq_ci(want_city, have_city) {
                    return Err(ValidationError::Consistency {
                        reason: format!(
                            "fills[{i}] worker {candidate_id:?} city {have_city:?} doesn't match contract city {want_city:?}"
                        ),
                    });
                }
            }
            if let (Some(want_state), Some(have_state)) = (ctx.state.as_deref(), worker.state.as_deref()) {
                if !eq_ci(want_state, have_state) {
                    return Err(ValidationError::Consistency {
                        reason: format!(
                            "fills[{i}] worker {candidate_id:?} state {have_state:?} doesn't match contract state {want_state:?}"
                        ),
                    });
                }
            }
            if let (Some(want_role), Some(have_role)) = (ctx.role.as_deref(), worker.role.as_deref()) {
                if !eq_ci(want_role, have_role) {
                    return Err(ValidationError::Consistency {
                        reason: format!(
                            "fills[{i}] worker {candidate_id:?} role {have_role:?} doesn't match contract role {want_role:?}"
                        ),
                    });
                }
            }

            // Name-mismatch is a warning, not an error — recruiters
            // sometimes send updated names through the proposal layer
            // before the roster is updated.
            if !proposed_name.is_empty() && !eq_ci(proposed_name, &worker.name) {
                findings.push(crate::Finding {
                    field: format!("fills[{i}].name"),
                    severity: crate::Severity::Warning,
                    message: format!(
                        "proposed name {proposed_name:?} differs from roster name {:?} for {candidate_id:?}",
                        worker.name
                    ),
                });
            }
        }

        Ok(Report {
            findings,
            elapsed_ms: started.elapsed().as_millis() as u64,
        })
    }
}

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

    fn lookup(records: Vec<WorkerRecord>) -> Arc<dyn WorkerLookup> {
        Arc::new(InMemoryWorkerLookup::from_records(records))
    }

    fn worker(id: &str, name: &str, status: &str, city: &str, state: &str, role: &str) -> WorkerRecord {
        WorkerRecord {
            candidate_id: id.into(),
            name: name.into(),
            status: status.into(),
            city: Some(city.into()),
            state: Some(state.into()),
            role: Some(role.into()),
            blacklisted_clients: vec![],
        }
    }

    #[test]
    fn wrong_artifact_type_fails_schema() {
        let v = FillValidator::new(lookup(vec![]));
        let r = v.validate(&Artifact::EmailDraft(json!({})));
        assert!(matches!(r, Err(ValidationError::Schema { .. })));
    }

    #[test]
    fn missing_fills_array_fails_schema() {
        let v = FillValidator::new(lookup(vec![]));
        let r = v.validate(&Artifact::FillProposal(json!({})));
        assert!(matches!(r, Err(ValidationError::Schema { field, .. }) if field == "fills"));
    }

    #[test]
    fn fill_without_candidate_id_fails() {
        let v = FillValidator::new(lookup(vec![]));
        let r = v.validate(&Artifact::FillProposal(json!({"fills": [{"name": "Jane"}]})));
        assert!(matches!(r, Err(ValidationError::Schema { field, .. }) if field.contains("candidate_id")));
    }

    #[test]
    fn well_formed_proposal_with_real_workers_passes() {
        let v = FillValidator::new(lookup(vec![
            worker("W-1", "Jane Doe", "active", "Toledo", "OH", "Welder"),
            worker("W-2", "John Smith", "active", "Toledo", "OH", "Welder"),
        ]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 2, "city": "Toledo", "state": "OH", "role": "Welder"},
            "fills": [
                {"candidate_id": "W-1", "name": "Jane Doe"},
                {"candidate_id": "W-2", "name": "John Smith"}
            ]
        })));
        assert!(r.is_ok(), "expected pass, got {:?}", r);
    }

    #[test]
    fn phantom_candidate_id_fails_consistency() {
        let v = FillValidator::new(lookup(vec![worker("W-1", "Jane", "active", "Toledo", "OH", "Welder")]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 1, "city": "Toledo", "state": "OH", "role": "Welder"},
            "fills": [{"candidate_id": "W-FAKE-99999", "name": "Imaginary"}]
        })));
        match r {
            Err(ValidationError::Consistency { reason }) => assert!(reason.contains("does not exist")),
            other => panic!("expected Consistency error, got {other:?}"),
        }
    }

    #[test]
    fn inactive_worker_fails_consistency() {
        let v = FillValidator::new(lookup(vec![worker("W-1", "Jane", "inactive", "Toledo", "OH", "Welder")]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 1},
            "fills": [{"candidate_id": "W-1", "name": "Jane"}]
        })));
        match r {
            Err(ValidationError::Consistency { reason }) => assert!(reason.contains("inactive")),
            other => panic!("expected Consistency error, got {other:?}"),
        }
    }

    #[test]
    fn wrong_city_fails_consistency() {
        let v = FillValidator::new(lookup(vec![worker("W-1", "Jane", "active", "Cincinnati", "OH", "Welder")]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 1, "city": "Toledo", "state": "OH", "role": "Welder"},
            "fills": [{"candidate_id": "W-1", "name": "Jane"}]
        })));
        match r {
            Err(ValidationError::Consistency { reason }) => assert!(reason.to_lowercase().contains("city")),
            other => panic!("expected Consistency error, got {other:?}"),
        }
    }

    #[test]
    fn wrong_role_fails_consistency() {
        let v = FillValidator::new(lookup(vec![worker("W-1", "Jane", "active", "Toledo", "OH", "Driver")]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 1, "city": "Toledo", "state": "OH", "role": "Welder"},
            "fills": [{"candidate_id": "W-1", "name": "Jane"}]
        })));
        match r {
            Err(ValidationError::Consistency { reason }) => assert!(reason.to_lowercase().contains("role")),
            other => panic!("expected Consistency error, got {other:?}"),
        }
    }

    #[test]
    fn count_mismatch_fails_completeness() {
        let v = FillValidator::new(lookup(vec![
            worker("W-1", "Jane", "active", "Toledo", "OH", "Welder"),
        ]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 2, "city": "Toledo", "state": "OH", "role": "Welder"},
            "fills": [{"candidate_id": "W-1", "name": "Jane"}]
        })));
        assert!(matches!(r, Err(ValidationError::Completeness { .. })));
    }

    #[test]
    fn duplicate_candidate_id_fails_consistency() {
        let v = FillValidator::new(lookup(vec![
            worker("W-1", "Jane", "active", "Toledo", "OH", "Welder"),
        ]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 2, "city": "Toledo", "state": "OH", "role": "Welder"},
            "fills": [
                {"candidate_id": "W-1", "name": "Jane"},
                {"candidate_id": "W-1", "name": "Jane"}
            ]
        })));
        match r {
            Err(ValidationError::Consistency { reason }) => assert!(reason.contains("duplicate")),
            other => panic!("expected Consistency error, got {other:?}"),
        }
    }

    #[test]
    fn blacklisted_worker_fails_policy() {
        let mut w = worker("W-1", "Jane", "active", "Toledo", "OH", "Welder");
        w.blacklisted_clients = vec!["CLI-00099".into()];
        let v = FillValidator::new(lookup(vec![w]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 1, "city": "Toledo", "state": "OH", "role": "Welder", "client_id": "CLI-00099"},
            "fills": [{"candidate_id": "W-1", "name": "Jane"}]
        })));
        assert!(matches!(r, Err(ValidationError::Policy { .. })));
    }

    #[test]
    fn name_mismatch_is_warning_not_error() {
        let v = FillValidator::new(lookup(vec![
            worker("W-1", "Jane Doe", "active", "Toledo", "OH", "Welder"),
        ]));
        let r = v.validate(&Artifact::FillProposal(json!({
            "_context": {"target_count": 1, "city": "Toledo", "state": "OH", "role": "Welder"},
            "fills": [{"candidate_id": "W-1", "name": "Janet Doe"}]
        })));
        let report = r.expect("name mismatch should be warning, not error");
        assert_eq!(report.findings.len(), 1);
        assert_eq!(report.findings[0].severity, crate::Severity::Warning);
        assert!(report.findings[0].message.contains("differs from roster"));
    }
}