package growthreport

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	"git.amiirkhl.ir/starcoach-hackathon/zarinpal-analytics-backend/internal/growth"
	"github.com/jackc/pgx/v5/pgxpool"
)

type HistoricalWin struct {
	growth.EventEffect
	EventTitleFA string    `json:"eventTitleFa"`
	StartDate    time.Time `json:"startDate"`
	EndDate      time.Time `json:"endDate"`
}

type PeerEvidence struct {
	State                    growth.PeerState         `json:"state"`
	Reason                   growth.SuppressionReason `json:"reason,omitempty"`
	EligiblePeerCount        int                      `json:"eligiblePeerCount"`
	CombinedPeerSessionCount int64                    `json:"combinedPeerSessionCount"`
	MedianPaidSessions       int64                    `json:"medianPaidSessions"`
	PercentileBPS            int64                    `json:"percentileBps"`
}

type Evidence struct {
	Forecast       growth.Forecast        `json:"forecast"`
	HistoricalWins []HistoricalWin        `json:"historicalWins"`
	Opportunities  []growth.Opportunity   `json:"opportunities"`
	Risks          []growth.Risk          `json:"risks"`
	Peer           *PeerEvidence          `json:"peer,omitempty"`
	FallbackBriefs []growth.CampaignBrief `json:"fallbackBriefs"`
}

type Analysis struct {
	Evidence      Evidence
	Encoded       json.RawMessage
	KnownEvidence map[string]struct{}
	Fallback      AICopy
	ShouldCallAI  bool
}

type Builder interface {
	Build(ctx context.Context, merchantID int64, terminalID string) (Analysis, error)
}

type PostgreSQLBuilder struct{ pool *pgxpool.Pool }

func NewPostgreSQLBuilder(pool *pgxpool.Pool) *PostgreSQLBuilder {
	return &PostgreSQLBuilder{pool: pool}
}

func (b *PostgreSQLBuilder) Build(ctx context.Context, merchantID int64, terminalID string) (Analysis, error) {
	catalog := growth.Catalog1405()
	var category string
	if err := b.pool.QueryRow(ctx, `SELECT category_title FROM merchants WHERE id=$1`, merchantID).Scan(&category); err != nil {
		return Analysis{}, fmt.Errorf("loading merchant category: %w", err)
	}
	rows, err := b.pool.Query(ctx, `WITH bounds AS (SELECT min(created_at AT TIME ZONE 'Asia/Tehran')::date first_day,max(created_at AT TIME ZONE 'Asia/Tehran')::date last_day FROM payment_sessions),
		days AS (SELECT generate_series(first_day,last_day,interval '1 day')::date local_date FROM bounds), scoped AS (
		SELECT (ps.created_at AT TIME ZONE 'Asia/Tehran')::date local_date,count(*) sessions,count(*) FILTER(WHERE ps.status IN ('Paid','Verified')) paid_sessions,coalesce(sum(ps.amount_rial) FILTER(WHERE ps.status IN ('Paid','Verified')),0) paid_amount
		FROM payment_sessions ps WHERE ps.merchant_id=$1 AND ($2='' OR ps.terminal_id=(SELECT id FROM terminals WHERE merchant_id=$1 AND source_key=$2)) GROUP BY 1)
		SELECT d.local_date,coalesce(s.sessions,0),coalesce(s.paid_sessions,0),coalesce(s.paid_amount,0) FROM days d LEFT JOIN scoped s USING(local_date) ORDER BY d.local_date`, merchantID, terminalID)
	if err != nil {
		return Analysis{}, fmt.Errorf("loading growth history: %w", err)
	}
	defer rows.Close()
	history := make([]growth.DailyPoint, 0, 366)
	for rows.Next() {
		var point growth.DailyPoint
		if err := rows.Scan(&point.Date, &point.SessionCount, &point.PaidSessionCount, &point.PaidAmountRial); err != nil {
			return Analysis{}, fmt.Errorf("scanning growth history: %w", err)
		}
		for _, event := range catalog {
			if !point.Date.Before(event.StartDate) && !point.Date.After(event.EndDate) {
				point.EventIDs = append(point.EventIDs, event.ID)
			}
		}
		history = append(history, point)
	}
	if err := rows.Err(); err != nil {
		return Analysis{}, fmt.Errorf("iterating growth history: %w", err)
	}
	var latest time.Time
	if err := b.pool.QueryRow(ctx, `SELECT max(created_at AT TIME ZONE 'Asia/Tehran')::date FROM payment_sessions`).Scan(&latest); err != nil {
		return Analysis{}, fmt.Errorf("loading dataset watermark date: %w", err)
	}
	forecastStart := latest.AddDate(0, 0, 1)
	peer, err := b.loadPeer(ctx, merchantID, terminalID)
	if err != nil {
		return Analysis{}, err
	}
	deterministic := growth.BuildDeterministicReport(growth.ReportInput{History: history, Catalog: catalog, ForecastStart: forecastStart, HorizonDays: 90, Category: category, Peer: &peer})
	events := make(map[string]growth.Event, len(catalog))
	for _, event := range catalog {
		events[event.ID] = event
	}
	evidence := Evidence{Forecast: deterministic.Forecast, Opportunities: deterministic.Opportunities, Risks: deterministic.Risks, FallbackBriefs: deterministic.FallbackBriefs}
	for _, effect := range deterministic.HistoricalWins {
		event := events[effect.EventID]
		evidence.HistoricalWins = append(evidence.HistoricalWins, HistoricalWin{EventEffect: effect, EventTitleFA: event.TitleFA, StartDate: event.StartDate, EndDate: event.EndDate})
	}
	if deterministic.Peer != nil {
		evidence.Peer = &PeerEvidence{State: deterministic.Peer.State, Reason: deterministic.Peer.Reason, EligiblePeerCount: deterministic.Peer.EligiblePeerCount, CombinedPeerSessionCount: deterministic.Peer.CombinedPeerSessions, MedianPaidSessions: deterministic.Peer.MedianPaidSessions, PercentileBPS: deterministic.Peer.PercentileBPS}
	}
	encoded, err := json.Marshal(evidence)
	if err != nil {
		return Analysis{}, fmt.Errorf("encoding deterministic growth evidence: %w", err)
	}
	known := map[string]struct{}{}
	for _, win := range evidence.HistoricalWins {
		known[win.EvidenceID] = struct{}{}
	}
	for _, opportunity := range evidence.Opportunities {
		known[opportunity.EvidenceID] = struct{}{}
	}
	for _, risk := range evidence.Risks {
		known[risk.EvidenceID] = struct{}{}
	}
	return Analysis{Evidence: evidence, Encoded: encoded, KnownEvidence: known, Fallback: convertFallback(deterministic.FallbackBriefs), ShouldCallAI: deterministic.Forecast.Confidence != growth.ConfidenceInsufficientData && (len(deterministic.Opportunities) > 0 || len(deterministic.Risks) > 0)}, nil
}

func (b *PostgreSQLBuilder) loadPeer(ctx context.Context, merchantID int64, terminalID string) (growth.PeerInput, error) {
	if terminalID != "" {
		return growth.PeerInput{TerminalScoped: true}, nil
	}
	var own int64
	if err := b.pool.QueryRow(ctx, `SELECT count(*) FROM payment_sessions WHERE merchant_id=$1 AND status IN ('Paid','Verified')`, merchantID).Scan(&own); err != nil {
		return growth.PeerInput{}, fmt.Errorf("loading merchant peer value: %w", err)
	}
	rows, err := b.pool.Query(ctx, `SELECT ps.merchant_id,count(*) FILTER(WHERE ps.status IN ('Paid','Verified')),count(*) FROM payment_sessions ps JOIN merchants m ON m.id=ps.merchant_id WHERE m.category_id=(SELECT category_id FROM merchants WHERE id=$1) AND ps.merchant_id<>$1 GROUP BY ps.merchant_id`, merchantID)
	if err != nil {
		return growth.PeerInput{}, fmt.Errorf("loading peer values: %w", err)
	}
	defer rows.Close()
	input := growth.PeerInput{MerchantPaidSessions: own}
	for rows.Next() {
		var peer growth.PeerMerchantValue
		var id int64
		if err := rows.Scan(&id, &peer.PaidSessions, &peer.SessionCount); err != nil {
			return growth.PeerInput{}, fmt.Errorf("scanning peer value: %w", err)
		}
		input.Peers = append(input.Peers, peer)
	}
	if err := rows.Err(); err != nil {
		return growth.PeerInput{}, fmt.Errorf("iterating peer values: %w", err)
	}
	return input, nil
}

func convertFallback(items []growth.CampaignBrief) AICopy {
	result := AICopy{Briefs: make([]CampaignBrief, 0, len(items))}
	for _, item := range items {
		result.Briefs = append(result.Briefs, CampaignBrief{Headline: item.HeadlineFA, Interpretation: item.GuidanceFA, OfferSuggestion: item.OfferFA, MessageSuggestion: item.MessageFA, PreparationAction: item.PreparationFA, Limitation: item.LimitationFA, EvidenceIDs: item.EvidenceIDs})
	}
	return result
}

type EvidenceTools struct{ analysis Analysis }

func NewEvidenceTools(analysis Analysis) EvidenceTools { return EvidenceTools{analysis: analysis} }
func (t EvidenceTools) Execute(_ context.Context, name string, arguments json.RawMessage) (json.RawMessage, error) {
	var args struct {
		EvidenceID string `json:"evidenceId"`
	}
	if err := json.Unmarshal(arguments, &args); err != nil {
		return nil, fmt.Errorf("invalid tool arguments: %w", err)
	}
	if len(args.EvidenceID) > 128 {
		return nil, fmt.Errorf("growth tool: invalid evidence id")
	}
	switch name {
	case "get_growth_context":
		return json.Marshal(map[string]any{"confidence": t.analysis.Evidence.Forecast.Confidence, "opportunityEvidenceIds": evidenceIDs(t.analysis.Evidence.Opportunities), "riskEvidenceIds": riskEvidenceIDs(t.analysis.Evidence.Risks)})
	case "get_peer_context":
		if t.analysis.Evidence.Peer == nil {
			return []byte(`{"state":"SUPPRESSED"}`), nil
		}
		return json.Marshal(t.analysis.Evidence.Peer)
	case "get_event_evidence":
		for _, item := range t.analysis.Evidence.HistoricalWins {
			if item.EvidenceID == args.EvidenceID {
				return json.Marshal(item)
			}
		}
		for _, item := range t.analysis.Evidence.Opportunities {
			if item.EvidenceID == args.EvidenceID {
				return json.Marshal(item)
			}
		}
	case "get_campaign_playbook":
		for _, item := range t.analysis.Fallback.Briefs {
			for _, id := range item.EvidenceIDs {
				if id == args.EvidenceID {
					return json.Marshal(item)
				}
			}
		}
	}
	return nil, errorsNewUnknownEvidence()
}
func evidenceIDs(items []growth.Opportunity) []string {
	result := make([]string, 0, len(items))
	for _, item := range items {
		result = append(result, item.EvidenceID)
	}
	return result
}
func riskEvidenceIDs(items []growth.Risk) []string {
	result := make([]string, 0, len(items))
	for _, item := range items {
		result = append(result, item.EvidenceID)
	}
	return result
}
func errorsNewUnknownEvidence() error { return fmt.Errorf("growth tool: unknown evidence") }