package inventory

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"sort"
	"strings"
	"time"
)

type EntityFilter struct {
	Limit              int
	AfterName, AfterID string
	Search             string
	EntityType         string
	Status             string
	Direction          string
}

type EntitySummary struct {
	ID             string     `json:"id"`
	EntityType     string     `json:"entityType"`
	CanonicalName  string     `json:"canonicalName"`
	DisplayName    string     `json:"displayName"`
	Status         string     `json:"status"`
	FirstSeenAt    *time.Time `json:"firstSeenAt"`
	LastSeenAt     *time.Time `json:"lastSeenAt,omitempty"`
	TombstonedAt   *time.Time `json:"tombstonedAt,omitempty"`
	FactCount      int        `json:"factCount"`
	OverrideCount  int        `json:"overrideCount"`
	RelationCount  int        `json:"relationCount"`
	SourceCount    int        `json:"sourceCount"`
	StaleFactCount int        `json:"staleFactCount"`
}

type AliasView struct {
	SourceID     string `json:"sourceId"`
	SourceName   string `json:"sourceName"`
	ExternalType string `json:"externalType"`
	ExternalID   string `json:"externalId"`
}
type FactView struct {
	FieldName  string          `json:"fieldName"`
	SourceID   string          `json:"sourceId"`
	SourceName string          `json:"sourceName"`
	Value      json.RawMessage `json:"value"`
	ObservedAt time.Time       `json:"observedAt"`
	Confidence float64         `json:"confidence"`
	ValidUntil *time.Time      `json:"validUntil,omitempty"`
	Stale      bool            `json:"stale"`
}
type OverrideView struct {
	FieldName string          `json:"fieldName"`
	Value     json.RawMessage `json:"value"`
	UserID    string          `json:"userId,omitempty"`
	UpdatedAt time.Time       `json:"updatedAt"`
}
type EffectiveValue struct {
	FieldName    string          `json:"fieldName"`
	Value        json.RawMessage `json:"value"`
	Origin       string          `json:"origin"`
	SourceID     string          `json:"sourceId,omitempty"`
	SourceName   string          `json:"sourceName,omitempty"`
	ObservedAt   *time.Time      `json:"observedAt,omitempty"`
	Confidence   *float64        `json:"confidence,omitempty"`
	Stale        bool            `json:"stale"`
	OverriddenAt *time.Time      `json:"overriddenAt,omitempty"`
}
type RelationView struct {
	ID               string     `json:"id"`
	Direction        string     `json:"direction"`
	RelationType     string     `json:"relationType"`
	PeerID           string     `json:"peerId"`
	PeerType         string     `json:"peerType"`
	PeerName         string     `json:"peerName"`
	PeerStatus       string     `json:"peerStatus"`
	PeerTombstonedAt *time.Time `json:"peerTombstonedAt,omitempty"`
	SourceID         string     `json:"sourceId"`
	SourceName       string     `json:"sourceName"`
	Confidence       float64    `json:"confidence"`
	Confirmed        bool       `json:"confirmed"`
	FirstSeenAt      *time.Time `json:"firstSeenAt"`
	LastSeenAt       *time.Time `json:"lastSeenAt,omitempty"`
	TombstonedAt     *time.Time `json:"tombstonedAt,omitempty"`
}
type EntityDetail struct {
	Entity    EntitySummary    `json:"entity"`
	Aliases   []AliasView      `json:"aliases"`
	Facts     []FactView       `json:"facts"`
	Overrides []OverrideView   `json:"overrides"`
	Effective []EffectiveValue `json:"effectiveValues"`
	Relations []RelationView   `json:"relations"`
}

func (f EntityFilter) Validate() error {
	if f.Limit < 1 || f.Limit > 100 {
		return errors.New("entity page limit must be between 1 and 100")
	}
	if len(f.Search) > 120 || len(f.EntityType) > 80 || len(f.Status) > 40 {
		return errors.New("entity filters exceed bounds")
	}
	if f.Direction != "asc" && f.Direction != "desc" {
		return errors.New("entity sort direction must be asc or desc")
	}
	return nil
}

func (r *Repository) SearchEntities(ctx context.Context, filter EntityFilter) ([]EntitySummary, error) {
	if err := filter.Validate(); err != nil {
		return nil, err
	}
	rows, err := r.pool.Query(ctx, `WITH projected AS (
SELECT e.id::text,e.entity_type,e.canonical_name,
 COALESCE(NULLIF(od.value #>> '{}',''),e.display_name) AS effective_name,
 COALESCE(NULLIF(os.value #>> '{}',''),e.status) AS effective_status,
 e.first_seen_at,e.last_seen_at,e.tombstoned_at,
 (SELECT count(*) FROM entity_facts f WHERE f.entity_id=e.id)::int AS fact_count,
 (SELECT count(*) FROM entity_overrides o WHERE o.entity_id=e.id)::int AS override_count,
 (SELECT count(*) FROM entity_relations rel WHERE rel.source_entity_id=e.id OR rel.target_entity_id=e.id)::int AS relation_count,
 (SELECT count(DISTINCT source_id) FROM entity_facts f WHERE f.entity_id=e.id)::int AS source_count,
 (SELECT count(*) FROM entity_facts f WHERE f.entity_id=e.id AND f.valid_until IS NOT NULL AND f.valid_until < now())::int AS stale_fact_count
FROM entities e
LEFT JOIN entity_overrides od ON od.entity_id=e.id AND od.field_name='displayName'
LEFT JOIN entity_overrides os ON os.entity_id=e.id AND os.field_name='status'
WHERE e.tombstoned_at IS NULL)
SELECT id,entity_type,canonical_name,effective_name,effective_status,first_seen_at,last_seen_at,tombstoned_at,fact_count,override_count,relation_count,source_count,stale_fact_count
FROM projected
WHERE ($1='' OR lower(effective_name) LIKE '%'||lower($1)||'%' OR lower(canonical_name) LIKE '%'||lower($1)||'%')
 AND ($2='' OR entity_type=$2) AND ($3='' OR effective_status=$3)
 AND ($4='' OR ($6='asc' AND (lower(effective_name),id) > (lower($4),$5)) OR ($6='desc' AND (lower(effective_name),id) < (lower($4),$5)))
ORDER BY CASE WHEN $6='asc' THEN lower(effective_name) END ASC, CASE WHEN $6='desc' THEN lower(effective_name) END DESC,
 CASE WHEN $6='asc' THEN id END ASC, CASE WHEN $6='desc' THEN id END DESC LIMIT $7`, strings.TrimSpace(filter.Search), filter.EntityType, filter.Status, filter.AfterName, filter.AfterID, filter.Direction, filter.Limit+1)
	if err != nil {
		return nil, fmt.Errorf("search entities: %w", err)
	}
	defer rows.Close()
	result := make([]EntitySummary, 0, filter.Limit+1)
	for rows.Next() {
		var item EntitySummary
		if err := rows.Scan(&item.ID, &item.EntityType, &item.CanonicalName, &item.DisplayName, &item.Status, &item.FirstSeenAt, &item.LastSeenAt, &item.TombstonedAt, &item.FactCount, &item.OverrideCount, &item.RelationCount, &item.SourceCount, &item.StaleFactCount); err != nil {
			return nil, fmt.Errorf("scan entity search: %w", err)
		}
		result = append(result, item)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("search entity rows: %w", err)
	}
	return result, nil
}

func (r *Repository) GetEntityDetail(ctx context.Context, id string) (EntityDetail, error) {
	rows, err := r.SearchEntitiesByID(ctx, id)
	if err != nil {
		return EntityDetail{}, err
	}
	if len(rows) == 0 {
		return EntityDetail{}, fmt.Errorf("get entity detail: %w", ErrNotFound)
	}
	detail := EntityDetail{Entity: rows[0], Aliases: []AliasView{}, Facts: []FactView{}, Overrides: []OverrideView{}, Effective: []EffectiveValue{}, Relations: []RelationView{}}
	aliasRows, err := r.pool.Query(ctx, `SELECT a.source_id::text,s.name,a.external_type,a.external_id FROM entity_aliases a JOIN data_sources s ON s.id=a.source_id WHERE a.entity_id=$1 ORDER BY s.name,a.external_type,a.external_id`, id)
	if err != nil {
		return EntityDetail{}, fmt.Errorf("list entity aliases: %w", err)
	}
	for aliasRows.Next() {
		var item AliasView
		if err := aliasRows.Scan(&item.SourceID, &item.SourceName, &item.ExternalType, &item.ExternalID); err != nil {
			aliasRows.Close()
			return EntityDetail{}, err
		}
		detail.Aliases = append(detail.Aliases, item)
	}
	aliasRows.Close()
	if err := aliasRows.Err(); err != nil {
		return EntityDetail{}, err
	}
	factRows, err := r.pool.Query(ctx, `SELECT f.field_name,f.source_id::text,s.name,f.value,f.observed_at,f.confidence,f.valid_until,(f.valid_until IS NOT NULL AND f.valid_until<now()) FROM entity_facts f JOIN data_sources s ON s.id=f.source_id WHERE f.entity_id=$1 ORDER BY f.field_name,(f.valid_until IS NOT NULL AND f.valid_until<now()),f.confidence DESC,f.observed_at DESC,f.source_id`, id)
	if err != nil {
		return EntityDetail{}, fmt.Errorf("list entity fact views: %w", err)
	}
	for factRows.Next() {
		var item FactView
		if err := factRows.Scan(&item.FieldName, &item.SourceID, &item.SourceName, &item.Value, &item.ObservedAt, &item.Confidence, &item.ValidUntil, &item.Stale); err != nil {
			factRows.Close()
			return EntityDetail{}, err
		}
		detail.Facts = append(detail.Facts, item)
	}
	factRows.Close()
	if err := factRows.Err(); err != nil {
		return EntityDetail{}, err
	}
	overrideRows, err := r.pool.Query(ctx, `SELECT field_name,value,COALESCE(user_id::text,''),updated_at FROM entity_overrides WHERE entity_id=$1 ORDER BY field_name`, id)
	if err != nil {
		return EntityDetail{}, fmt.Errorf("list entity overrides: %w", err)
	}
	for overrideRows.Next() {
		var item OverrideView
		if err := overrideRows.Scan(&item.FieldName, &item.Value, &item.UserID, &item.UpdatedAt); err != nil {
			overrideRows.Close()
			return EntityDetail{}, err
		}
		detail.Overrides = append(detail.Overrides, item)
	}
	overrideRows.Close()
	if err := overrideRows.Err(); err != nil {
		return EntityDetail{}, err
	}
	detail.Effective = effectiveValues(detail.Facts, detail.Overrides)
	relationRows, err := r.pool.Query(ctx, `SELECT rel.id::text,CASE WHEN rel.source_entity_id=$1 THEN 'outgoing' ELSE 'incoming' END,rel.relation_type,peer.id::text,peer.entity_type,peer.display_name,CASE WHEN peer.tombstoned_at IS NULL THEN peer.status ELSE 'Ontbrekende entiteit' END,peer.tombstoned_at,rel.source_id::text,s.name,rel.confidence,rel.confirmed,rel.first_seen_at,rel.last_seen_at,rel.tombstoned_at FROM entity_relations rel JOIN entities peer ON peer.id=CASE WHEN rel.source_entity_id=$1 THEN rel.target_entity_id ELSE rel.source_entity_id END JOIN data_sources s ON s.id=rel.source_id WHERE rel.source_entity_id=$1 OR rel.target_entity_id=$1 ORDER BY rel.relation_type,peer.display_name,rel.id`, id)
	if err != nil {
		return EntityDetail{}, fmt.Errorf("list entity relation views: %w", err)
	}
	for relationRows.Next() {
		var item RelationView
		if err := relationRows.Scan(&item.ID, &item.Direction, &item.RelationType, &item.PeerID, &item.PeerType, &item.PeerName, &item.PeerStatus, &item.PeerTombstonedAt, &item.SourceID, &item.SourceName, &item.Confidence, &item.Confirmed, &item.FirstSeenAt, &item.LastSeenAt, &item.TombstonedAt); err != nil {
			relationRows.Close()
			return EntityDetail{}, err
		}
		detail.Relations = append(detail.Relations, item)
	}
	relationRows.Close()
	if err := relationRows.Err(); err != nil {
		return EntityDetail{}, err
	}
	return detail, nil
}

var ErrNotFound = errors.New("inventory entity not found")

func (r *Repository) SearchEntitiesByID(ctx context.Context, id string) ([]EntitySummary, error) {
	rows, err := r.pool.Query(ctx, `SELECT e.id::text,e.entity_type,e.canonical_name,COALESCE(NULLIF(od.value #>> '{}',''),e.display_name),COALESCE(NULLIF(os.value #>> '{}',''),e.status),e.first_seen_at,e.last_seen_at,e.tombstoned_at,(SELECT count(*) FROM entity_facts f WHERE f.entity_id=e.id)::int,(SELECT count(*) FROM entity_overrides o WHERE o.entity_id=e.id)::int,(SELECT count(*) FROM entity_relations rel WHERE rel.source_entity_id=e.id OR rel.target_entity_id=e.id)::int,(SELECT count(DISTINCT source_id) FROM entity_facts f WHERE f.entity_id=e.id)::int,(SELECT count(*) FROM entity_facts f WHERE f.entity_id=e.id AND f.valid_until IS NOT NULL AND f.valid_until<now())::int FROM entities e LEFT JOIN entity_overrides od ON od.entity_id=e.id AND od.field_name='displayName' LEFT JOIN entity_overrides os ON os.entity_id=e.id AND os.field_name='status' WHERE e.id=$1`, id)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var result []EntitySummary
	for rows.Next() {
		var item EntitySummary
		if err := rows.Scan(&item.ID, &item.EntityType, &item.CanonicalName, &item.DisplayName, &item.Status, &item.FirstSeenAt, &item.LastSeenAt, &item.TombstonedAt, &item.FactCount, &item.OverrideCount, &item.RelationCount, &item.SourceCount, &item.StaleFactCount); err != nil {
			return nil, err
		}
		result = append(result, item)
	}
	return result, rows.Err()
}

func effectiveValues(facts []FactView, overrides []OverrideView) []EffectiveValue {
	overrideByField := make(map[string]OverrideView, len(overrides))
	for _, item := range overrides {
		overrideByField[item.FieldName] = item
	}
	fields := make(map[string]struct{}, len(facts)+len(overrides))
	for _, item := range facts {
		fields[item.FieldName] = struct{}{}
	}
	for _, item := range overrides {
		fields[item.FieldName] = struct{}{}
	}
	names := make([]string, 0, len(fields))
	for name := range fields {
		names = append(names, name)
	}
	sort.Strings(names)
	result := make([]EffectiveValue, 0, len(names))
	for _, name := range names {
		if item, ok := overrideByField[name]; ok {
			at := item.UpdatedAt
			result = append(result, EffectiveValue{FieldName: name, Value: item.Value, Origin: "override", OverriddenAt: &at})
			continue
		}
		for _, fact := range facts {
			if fact.FieldName == name {
				observed, confidence := fact.ObservedAt, fact.Confidence
				result = append(result, EffectiveValue{FieldName: name, Value: fact.Value, Origin: "discovered", SourceID: fact.SourceID, SourceName: fact.SourceName, ObservedAt: &observed, Confidence: &confidence, Stale: fact.Stale})
				break
			}
		}
	}
	return result
}