<?php
defined( 'ABSPATH' ) || exit;

/**
 * Deterministic Trace Audit.
 *
 * Local rules-based checks over a Demand trace. Repeatable, side-effect-free,
 * no external API, no LLM, no state stored. Pure function over the trace array
 * as returned by SA_Orch_Rest::get_demand_trace().
 *
 * This is the FLOOR of a four-layer review stack:
 *
 *   (1) Trace data                — what is in the database / Asterion ledger.
 *   (2) Deterministic Trace Audit — this layer. Rules-only, repeatable, fast.
 *   (3) Strategy LLM Review       — FUTURE. Sits above this layer and compares
 *                                   its reasoning against the deterministic audit.
 *                                   The audit becomes a sanity-check / fallback
 *                                   when the LLM layer is wired up.
 *   (4) Human arbitration         — final meaning. Always wins.
 *
 * The class name `SA_Orch_Reasoning` is preserved as the long-term contract;
 * v0.4 implements only the deterministic layer. When LLM review is added, it
 * will live alongside this audit (the audit will not be replaced).
 *
 * Rules implemented in v0.4 (minimal deterministic set):
 *   - Closure authority invalid (acceptance_affirmed by non-stakeholder)
 *   - projection_type ↔ plan_link count mismatch
 *   - Affirmation without prior result_claimed
 *   - prior_event_id chain integrity
 *   - Multiple arbitrations on same Demand → scope drift
 *   - projection_type other than scope-direct(-no-plan) → scope drift
 *   - truth_class=derived on arbitration → scope drift
 *   - dispute → affirm pattern → informational note
 *   - acceptance_revoked present → informational note
 *   - Needs Human Arbitration triggers (v0.4.1):
 *       * closure_authority_valid = false
 *       * truth_class=derived AND no acceptance events
 *       * multiple arbitrations on same Demand
 *       * acceptance_disputed is the latest event
 */
class SA_Orch_Reasoning {

    /**
     * Mode constant. v0.4 is deterministic-only; the LLM seam is future work.
     */
    const MODE = 'deterministic';

    /**
     * Evaluate a trace and return the deterministic audit report.
     *
     * Input shape: trace array as returned by SA_Orch_Rest::get_demand_trace().
     *
     * Output:
     *   [
     *     'mode'                           => 'deterministic',
     *     'summary'                        => string,
     *     'inconsistencies'                => string[],
     *     'scope_drift'                    => string[],
     *     'notes'                          => string[],
     *     'closure_confidence'             => 'high' | 'medium' | 'low' | 'n/a',
     *     'closure_confidence_explanation' => string,
     *     'needs_human_arbitration'        => bool,
     *     'human_arbitration_message'      => string,    // verbatim user-facing line
     *     'human_arbitration_triggers'     => string[],  // reasons firing the flag
     *   ]
     */
    public static function evaluate( array $trace ) {
        $arbs      = isset( $trace['arbitrations'] ) ? (array) $trace['arbitrations'] : [];
        $links     = isset( $trace['plan_links'] )   ? (array) $trace['plan_links']   : [];
        $events    = isset( $trace['acceptance'] )   ? (array) $trace['acceptance']   : [];
        $basic     = $trace['closure_state_basic']      ?? null;
        $authority = $trace['closure_authority_valid']  ?? null;

        // Event-type flags
        $has_claim   = false;
        $has_dispute = false;
        $has_affirm  = false;
        $has_revoke  = false;
        foreach ( $events as $e ) {
            if ( $e->event_type === 'result_claimed' )      $has_claim   = true;
            if ( $e->event_type === 'acceptance_disputed' ) $has_dispute = true;
            if ( $e->event_type === 'acceptance_affirmed' ) $has_affirm  = true;
            if ( $e->event_type === 'acceptance_revoked' )  $has_revoke  = true;
        }

        $inconsistencies = [];
        $drift           = [];
        $notes           = [];

        // --- Inconsistencies ---

        // Closure authority invalid: latest acceptance_affirmed by non-stakeholder
        if ( $authority === false ) {
            $latest_affirm = null;
            foreach ( array_reverse( $events ) as $e ) {
                if ( $e->event_type === 'acceptance_affirmed' ) { $latest_affirm = $e; break; }
            }
            if ( $latest_affirm ) {
                $inconsistencies[] = "Closure authority invalid: acceptance_affirmed event #{$latest_affirm->id} authored by actor_role='{$latest_affirm->actor_role}' (must be 'stakeholder' for authoritative closure).";
            }
        }

        // projection_type vs plan_link count mismatch
        foreach ( $arbs as $arb ) {
            $arb_id = (int) $arb->id;
            $arb_links = count( array_filter( $links, function ( $l ) use ( $arb_id ) {
                return (int) $l->arbitration_id === $arb_id;
            } ) );
            if ( $arb->projection_type === 'scope-direct-no-plan' && $arb_links > 0 ) {
                $inconsistencies[] = "Arbitration #{$arb->id} declares projection_type='scope-direct-no-plan' but has {$arb_links} plan link(s) — inconsistent.";
            }
            if ( in_array( $arb->projection_type, [ 'scope-direct', 'scope-decomposed', 'scope-merged' ], true ) && $arb_links === 0 ) {
                $inconsistencies[] = "Arbitration #{$arb->id} declares projection_type='{$arb->projection_type}' but has no plan links — projection promised a Plan but none recorded.";
            }
        }

        // Affirmation without claim (closure path is incomplete)
        if ( $has_affirm && ! $has_claim ) {
            $inconsistencies[] = "Acceptance was affirmed without any prior result_claimed event — closure path is incomplete.";
        }

        // prior_event_id chain integrity
        $event_ids = array_map( function ( $e ) { return (int) $e->id; }, $events );
        foreach ( $events as $e ) {
            if ( $e->prior_event_id !== null && $e->prior_event_id !== '' ) {
                $prior = (int) $e->prior_event_id;
                if ( $prior > 0 && ! in_array( $prior, $event_ids, true ) ) {
                    $inconsistencies[] = "Event #{$e->id} references prior_event_id={$prior}, which is not in this Demand's event chain.";
                }
            }
        }

        // --- Scope drift ---

        if ( count( $arbs ) > 1 ) {
            $drift[] = "Demand has " . count( $arbs ) . " arbitrations recorded — review for re-interpretation across arbitration moments.";
        }

        foreach ( $arbs as $arb ) {
            if ( ! in_array( $arb->projection_type, [ 'scope-direct', 'scope-direct-no-plan' ], true ) ) {
                $drift[] = "Arbitration #{$arb->id} uses projection_type='{$arb->projection_type}' — explicit scope transformation. Verify the Plan honors the original Demand intent.";
            }
            if ( $arb->truth_class === 'derived' ) {
                $drift[] = "Arbitration #{$arb->id} has truth_class='derived' — Demand was reconstructed from Plan-side evidence. Original scope is not directly verifiable.";
            }
        }

        // --- Notes (informational) ---

        if ( $has_dispute && $has_affirm ) {
            $notes[] = "This Demand experienced a dispute before its current affirmation. Review the dispute → affirmation transition for completeness of resolution.";
        }
        if ( $has_revoke ) {
            $notes[] = "An acceptance_revoked event is present — a previously-affirmed acceptance was withdrawn.";
        }
        if ( ! empty( $events ) && ! $has_claim && ! $has_dispute && ! $has_affirm && ! $has_revoke ) {
            $notes[] = "Acceptance events present but none of the standard types (claim/dispute/affirm/revoke) — review event_type values.";
        }

        // --- Summary + confidence ---

        $summary    = self::build_summary( $arbs, $links, $events, $basic, $authority );
        $confidence = self::compute_confidence(
            $basic,
            $authority,
            $has_dispute,
            $has_revoke,
            count( $inconsistencies ),
            count( $drift ),
            count( $events )
        );

        // --- Needs Human Arbitration (v0.4.1) ---

        $human = self::compute_human_arbitration( $arbs, $events, $authority );

        return [
            'mode'                           => self::MODE,
            'summary'                        => $summary,
            'inconsistencies'                => $inconsistencies,
            'scope_drift'                    => $drift,
            'notes'                          => $notes,
            'closure_confidence'             => $confidence['level'],
            'closure_confidence_explanation' => $confidence['explanation'],
            'needs_human_arbitration'        => $human['required'],
            'human_arbitration_message'      => $human['message'],
            'human_arbitration_triggers'     => $human['triggers'],
        ];
    }

    /**
     * Determine whether this trace requires human arbitration.
     *
     * Triggers (any one is sufficient):
     *   1. closure_authority_valid = false (latest acceptance_affirmed by non-stakeholder).
     *   2. arbitration carries truth_class='derived' AND no acceptance events exist
     *      (Demand was reconstructed from Plan-side evidence and never confirmed).
     *   3. multiple arbitrations on the same Demand (re-interpretation requires
     *      human reconciliation).
     *   4. latest event is acceptance_disputed (dispute is unresolved).
     *
     * The human arbitration verdict is the deterministic layer's escalation
     * signal. It is independent of closure_confidence — a Demand can be
     * "open" and still require human arbitration if the conditions warrant.
     */
    private static function compute_human_arbitration( $arbs, $events, $authority ) {
        $triggers = [];

        // 1. closure_authority_valid = false
        if ( $authority === false ) {
            $triggers[] = "closure_authority_valid is false (acceptance_affirmed event was authored by a non-stakeholder actor).";
        }

        // 2. derived arbitration without acceptance events
        $has_derived_arb = false;
        foreach ( $arbs as $a ) {
            if ( ( $a->truth_class ?? null ) === 'derived' ) { $has_derived_arb = true; break; }
        }
        if ( $has_derived_arb && count( $events ) === 0 ) {
            $triggers[] = "Demand is derived (truth_class='derived' on arbitration) and has no acceptance events — original stakeholder intent is unverified.";
        }

        // 3. multiple arbitrations on the same Demand
        if ( count( $arbs ) > 1 ) {
            $triggers[] = count( $arbs ) . " arbitrations exist on the same Demand — re-interpretation requires human reconciliation.";
        }

        // 4. latest event is acceptance_disputed
        if ( ! empty( $events ) ) {
            $latest = end( $events );
            if ( ( $latest->event_type ?? null ) === 'acceptance_disputed' ) {
                $triggers[] = "Latest event is acceptance_disputed — dispute is unresolved and requires human follow-up before closure can be trusted.";
            }
        }

        return [
            'required' => ! empty( $triggers ),
            'message'  => 'This trace requires human arbitration before closure can be trusted.',
            'triggers' => $triggers,
        ];
    }

    private static function build_summary( $arbs, $links, $events, $basic, $authority ) {
        $arb_n   = count( $arbs );
        $link_n  = count( $links );
        $event_n = count( $events );

        if ( $arb_n === 0 && $event_n === 0 ) {
            return "No arbitration and no acceptance events for this Demand. The Demand may be unrecognized by SA-Orchestration, or the surface_ref may be wrong.";
        }

        $bits   = [];
        $bits[] = "{$arb_n} arbitration"   . ( $arb_n   === 1 ? '' : 's' );
        $bits[] = "{$link_n} plan link"    . ( $link_n  === 1 ? '' : 's' );
        $bits[] = "{$event_n} acceptance event" . ( $event_n === 1 ? '' : 's' );

        $event_seq = '';
        if ( $event_n > 0 ) {
            $sequence = [];
            foreach ( $events as $e ) $sequence[] = $e->event_type;
            $event_seq = ' Sequence: ' . implode( ' → ', $sequence ) . '.';
        }

        $closure_phrase = '';
        if ( $basic === 'closed' ) {
            if ( $authority === true ) {
                $closure_phrase = ' Currently closed (stakeholder-affirmed).';
            } elseif ( $authority === false ) {
                $closure_phrase = ' Marked closed but closure authority is invalid (non-stakeholder affirmed).';
            } else {
                $closure_phrase = ' Currently closed.';
            }
        } elseif ( is_string( $basic ) && strpos( $basic, 'open:' ) === 0 ) {
            $closure_phrase = " Currently open ({$basic}).";
        } elseif ( $basic === 'no-events' ) {
            $closure_phrase = ' No acceptance events.';
        }

        return implode( ', ', $bits ) . '.' . $event_seq . $closure_phrase;
    }

    private static function compute_confidence( $basic, $authority, $has_dispute, $has_revoke, $inc_count, $drift_count, $event_count ) {
        // No events — confidence not meaningful
        if ( $event_count === 0 || $basic === 'no-events' ) {
            return [
                'level'       => 'n/a',
                'explanation' => 'No acceptance events to evaluate; closure confidence is not yet meaningful.',
            ];
        }

        // Open states
        if ( is_string( $basic ) && strpos( $basic, 'open:' ) === 0 ) {
            return [
                'level'       => 'low',
                'explanation' => "Demand is currently {$basic}; closure has not been claimed and confirmed.",
            ];
        }

        // Closed but authority invalid
        if ( $basic === 'closed' && $authority === false ) {
            return [
                'level'       => 'low',
                'explanation' => 'Closed by non-stakeholder actor; closure_authority_valid=false. Treat as not authoritatively closed.',
            ];
        }

        // Closed with stakeholder authority
        if ( $basic === 'closed' && $authority === true ) {
            if ( $inc_count > 0 ) {
                return [
                    'level'       => 'low',
                    'explanation' => "Closed by stakeholder, but {$inc_count} inconsistenc" . ( $inc_count === 1 ? 'y' : 'ies' ) . ' detected. Review before treating as final.',
                ];
            }
            $reasons = [];
            if ( $has_dispute )  $reasons[] = 'a prior dispute was recorded';
            if ( $has_revoke )   $reasons[] = 'an acceptance_revoked event exists';
            if ( $drift_count )  $reasons[] = "{$drift_count} potential scope-drift indicator" . ( $drift_count === 1 ? '' : 's' );
            if ( count( $reasons ) === 0 ) {
                return [
                    'level'       => 'high',
                    'explanation' => 'Closed by stakeholder with a clean event chain and no scope drift detected.',
                ];
            }
            return [
                'level'       => 'medium',
                'explanation' => 'Closed by stakeholder, but ' . implode( '; ', $reasons ) . '. Review history before treating as routine.',
            ];
        }

        // Fall-through (unrecognized basic state)
        return [ 'level' => 'low', 'explanation' => "Unrecognized closure_state_basic value: '{$basic}'." ];
    }
}