package controlplane

import (
	"context"
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"aigw/internal/auth"
	"aigw/internal/domain"

	"github.com/jackc/pgx/v5"
)

func (s *Store) LoadSnapshot(ctx context.Context) (Snapshot, error) {
	tx, err := s.db.BeginTx(ctx, pgx.TxOptions{IsoLevel: pgx.RepeatableRead, AccessMode: pgx.ReadOnly})
	if err != nil {
		return Snapshot{}, fmt.Errorf("begin snapshot transaction: %w", err)
	}
	defer tx.Rollback(ctx)

	var result Snapshot
	if err := tx.QueryRow(ctx, `SELECT generation FROM control_state WHERE singleton = TRUE`).Scan(&result.Generation); err != nil {
		return Snapshot{}, fmt.Errorf("read snapshot generation: %w", err)
	}

	providers, err := s.loadProviders(ctx, tx)
	if err != nil {
		return Snapshot{}, err
	}
	result.Models, err = loadModels(ctx, tx, providers)
	if err != nil {
		return Snapshot{}, err
	}
	result.APIKeys, err = loadAPIKeys(ctx, tx)
	if err != nil {
		return Snapshot{}, err
	}
	result.Limits, err = loadLimitPolicies(ctx, tx)
	if err != nil {
		return Snapshot{}, err
	}
	if err := tx.Commit(ctx); err != nil {
		return Snapshot{}, fmt.Errorf("commit snapshot transaction: %w", err)
	}
	return result, nil
}

func loadLimitPolicies(ctx context.Context, tx pgx.Tx) ([]domain.LimitPolicy, error) {
	rows, err := tx.Query(ctx, `
		SELECT tenant_id::text, project_id::text, requests_per_minute, tokens_per_minute,
		       concurrent_requests, monthly_spend_micros
		FROM project_limits`)
	if err != nil {
		return nil, fmt.Errorf("query project limits: %w", err)
	}
	defer rows.Close()
	result := make([]domain.LimitPolicy, 0)
	for rows.Next() {
		var policy domain.LimitPolicy
		if err := rows.Scan(&policy.TenantID, &policy.ProjectID, &policy.RequestsPerMinute,
			&policy.TokensPerMinute, &policy.Concurrent, &policy.MonthlySpendMicros); err != nil {
			return nil, fmt.Errorf("scan project limit: %w", err)
		}
		result = append(result, policy)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("read project limits: %w", err)
	}
	return result, nil
}

func (s *Store) loadProviders(ctx context.Context, tx pgx.Tx) (map[string]domain.Provider, error) {
	rows, err := tx.Query(ctx, `
		SELECT id::text, name, protocol, base_url, api_key_ciphertext
		FROM providers
		WHERE enabled = TRUE
		ORDER BY name`)
	if err != nil {
		return nil, fmt.Errorf("query providers: %w", err)
	}
	defer rows.Close()
	providers := make(map[string]domain.Provider)
	for rows.Next() {
		var id, name, protocol, baseURL string
		var ciphertext []byte
		if err := rows.Scan(&id, &name, &protocol, &baseURL, &ciphertext); err != nil {
			return nil, fmt.Errorf("scan provider: %w", err)
		}
		apiKey, err := s.cipher.Decrypt(ciphertext)
		if err != nil {
			return nil, fmt.Errorf("decrypt provider %q credential: %w", name, err)
		}
		providers[id] = domain.Provider{ID: id, Protocol: domain.Protocol(protocol), BaseURL: strings.TrimRight(baseURL, "/"), APIKey: apiKey}
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("read providers: %w", err)
	}
	return providers, nil
}

func loadModels(ctx context.Context, tx pgx.Tx, providers map[string]domain.Provider) ([]domain.Model, error) {
	rows, err := tx.Query(ctx, `
		SELECT m.id::text, m.public_id, m.display_name, m.description, m.owned_by,
		       m.input_modalities, m.output_modalities, m.context_window, m.max_output_tokens,
		       m.capabilities, m.regions, m.lifecycle, m.released_at, m.deprecated_at,
		       m.retired_at, COALESCE(m.replacement_model,''),
		       pv.id::text, pv.version, pv.currency, pv.effective_from,
		       pv.input_price_micros_per_million, pv.output_price_micros_per_million,
		       pv.cache_read_price_micros_per_million, pv.cache_write_price_micros_per_million,
		       r.provider_id::text, r.upstream_model, r.priority, r.weight
		FROM models m
		JOIN LATERAL (
			SELECT * FROM model_price_versions v WHERE v.model_id=m.id
			  AND v.effective_from <= now() AND (v.effective_to IS NULL OR v.effective_to > now())
			ORDER BY v.effective_from DESC LIMIT 1
		) pv ON TRUE
		JOIN model_routes r ON r.model_id = m.id AND r.enabled = TRUE
		JOIN providers p ON p.id = r.provider_id AND p.enabled = TRUE
		WHERE m.enabled = TRUE AND m.lifecycle <> 'retired'
		ORDER BY m.public_id, r.priority, r.created_at`)
	if err != nil {
		return nil, fmt.Errorf("query model routes: %w", err)
	}
	defer rows.Close()
	models := make([]domain.Model, 0)
	index := make(map[string]int)
	for rows.Next() {
		var modelID, publicID, displayName, description, ownedBy, replacement, providerID, upstreamModel string
		var inputModalitiesJSON, outputModalitiesJSON, capabilitiesJSON, regionsJSON []byte
		var contextWindow, maxOutput int64
		var lifecycle, priceVersionID, priceCurrency string
		var releasedAt, deprecatedAt, retiredAt *time.Time
		var priceVersion int
		var priceEffectiveFrom time.Time
		var inputPrice, outputPrice, cacheReadPrice, cacheWritePrice int64
		var priority, weight int
		if err := rows.Scan(&modelID, &publicID, &displayName, &description, &ownedBy,
			&inputModalitiesJSON, &outputModalitiesJSON, &contextWindow, &maxOutput,
			&capabilitiesJSON, &regionsJSON, &lifecycle, &releasedAt, &deprecatedAt, &retiredAt, &replacement,
			&priceVersionID, &priceVersion, &priceCurrency, &priceEffectiveFrom,
			&inputPrice, &outputPrice, &cacheReadPrice, &cacheWritePrice,
			&providerID, &upstreamModel, &priority, &weight); err != nil {
			return nil, fmt.Errorf("scan model route: %w", err)
		}
		provider, ok := providers[providerID]
		if !ok {
			continue
		}
		position, exists := index[publicID]
		if !exists {
			var inputModalities, outputModalities, capabilities, regions []string
			if err := json.Unmarshal(inputModalitiesJSON, &inputModalities); err != nil {
				return nil, fmt.Errorf("decode model input modalities: %w", err)
			}
			if err := json.Unmarshal(outputModalitiesJSON, &outputModalities); err != nil {
				return nil, fmt.Errorf("decode model output modalities: %w", err)
			}
			if err := json.Unmarshal(capabilitiesJSON, &capabilities); err != nil {
				return nil, fmt.Errorf("decode model capabilities: %w", err)
			}
			if err := json.Unmarshal(regionsJSON, &regions); err != nil {
				return nil, fmt.Errorf("decode model regions: %w", err)
			}
			position = len(models)
			index[publicID] = position
			models = append(models, domain.Model{
				ID: publicID, DisplayName: displayName, Description: description, OwnedBy: ownedBy,
				InputModalities: inputModalities, OutputModalities: outputModalities,
				ContextWindow: contextWindow, MaxOutputTokens: maxOutput, Capabilities: capabilities,
				Regions: regions, Lifecycle: lifecycle, ReleasedAt: releasedAt, DeprecatedAt: deprecatedAt,
				RetiredAt: retiredAt, ReplacementModel: replacement, PriceVersionID: priceVersionID,
				PriceVersion: priceVersion, PriceCurrency: priceCurrency, PriceEffectiveFrom: priceEffectiveFrom,
				InputPriceMicrosPerMillion: inputPrice, OutputPriceMicrosPerMillion: outputPrice,
				CacheReadPriceMicrosPerMillion: cacheReadPrice, CacheWritePriceMicrosPerMillion: cacheWritePrice,
			})
			_ = modelID
		}
		models[position].Routes = append(models[position].Routes, domain.Route{
			Provider: provider, UpstreamModel: upstreamModel, Priority: priority, Weight: weight,
		})
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("read model routes: %w", err)
	}
	byID := make(map[string]int, len(models))
	for i := range models {
		byID[models[i].ID] = i
	}
	aliasRows, err := tx.Query(ctx, `SELECT a.alias, m.public_id FROM model_aliases a JOIN models m ON m.id=a.model_id`)
	if err != nil {
		return nil, fmt.Errorf("query model aliases: %w", err)
	}
	for aliasRows.Next() {
		var alias, publicID string
		if err := aliasRows.Scan(&alias, &publicID); err != nil {
			aliasRows.Close()
			return nil, err
		}
		if position, ok := byID[publicID]; ok {
			models[position].Aliases = append(models[position].Aliases, alias)
		}
	}
	aliasRows.Close()
	tenantRows, err := tx.Query(ctx, `SELECT m.public_id, a.tenant_id::text FROM model_tenant_allowlist a JOIN models m ON m.id=a.model_id`)
	if err != nil {
		return nil, fmt.Errorf("query model tenant allowlist: %w", err)
	}
	for tenantRows.Next() {
		var publicID, tenantID string
		if err := tenantRows.Scan(&publicID, &tenantID); err != nil {
			tenantRows.Close()
			return nil, err
		}
		if position, ok := byID[publicID]; ok {
			if models[position].AllowedTenantIDs == nil {
				models[position].AllowedTenantIDs = map[string]struct{}{}
			}
			models[position].AllowedTenantIDs[tenantID] = struct{}{}
		}
	}
	tenantRows.Close()
	keyRows, err := tx.Query(ctx, `SELECT m.public_id, a.api_key_id::text FROM api_key_model_allowlist a JOIN models m ON m.id=a.model_id`)
	if err != nil {
		return nil, fmt.Errorf("query model key allowlist: %w", err)
	}
	for keyRows.Next() {
		var publicID, keyID string
		if err := keyRows.Scan(&publicID, &keyID); err != nil {
			keyRows.Close()
			return nil, err
		}
		if position, ok := byID[publicID]; ok {
			if models[position].AllowedKeyIDs == nil {
				models[position].AllowedKeyIDs = map[string]struct{}{}
			}
			models[position].AllowedKeyIDs[keyID] = struct{}{}
		}
	}
	keyRows.Close()
	return models, nil
}

func loadAPIKeys(ctx context.Context, tx pgx.Tx) ([]auth.HashedKeyRecord, error) {
	rows, err := tx.Query(ctx, `
		SELECT k.id::text, k.key_hash, k.tenant_id::text, k.project_id::text, k.scopes
		FROM api_keys k
		JOIN tenants t ON t.id = k.tenant_id AND t.status = 'active'
		JOIN projects p ON p.id = k.project_id AND p.status = 'active'
		WHERE k.status = 'active'`)
	if err != nil {
		return nil, fmt.Errorf("query API keys: %w", err)
	}
	defer rows.Close()
	records := make([]auth.HashedKeyRecord, 0)
	for rows.Next() {
		var keyID, tenantID, projectID string
		var hashBytes, scopesJSON []byte
		if err := rows.Scan(&keyID, &hashBytes, &tenantID, &projectID, &scopesJSON); err != nil {
			return nil, fmt.Errorf("scan API key: %w", err)
		}
		if len(hashBytes) != sha256.Size {
			return nil, fmt.Errorf("API key %s has invalid hash length", keyID)
		}
		var hash [sha256.Size]byte
		copy(hash[:], hashBytes)
		var scopes []string
		if err := json.Unmarshal(scopesJSON, &scopes); err != nil {
			return nil, fmt.Errorf("decode API key %s scopes: %w", keyID, err)
		}
		records = append(records, auth.HashedKeyRecord{Hash: hash, Principal: domain.Principal{
			KeyID: keyID, TenantID: tenantID, ProjectID: projectID, Scopes: scopes,
		}})
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("read API keys: %w", err)
	}
	return records, nil
}