package service

import (
	"crypto/sha256"
	"encoding/json"
	"fmt"

	"github.com/peterqiu0516/sub-store/internal/database"
	"github.com/peterqiu0516/sub-store/internal/model"
)

// egressCacheKeySkip lists node fields excluded from the egress cache key so
// the key stays stable across pipeline stages (parse → filter → alias tag →
// rename) and matches the key the background probe wrote.
var egressCacheKeySkip = map[string]bool{
	"id": true, "name": true, "_sourceAlias": true, "_previewId": true,
	"latencyMs": true, "latencyError": true,
	"egressIp": true, "egressCountry": true, "egressRegion": true, "egressError": true,
	"country": true, "countryCode": true, "region": true, "city": true, "isp": true, "flag": true, "cached": true,
}

// EgressCacheKey returns the source_cache key for a node's egress probe
// result. Pushed down from the handler (HH-773) so the download pipeline
// reads the exact entries the probe wrote.
func EgressCacheKey(node model.ProxyNode) string {
	clean := model.ProxyNode{}
	for k, v := range node {
		if !egressCacheKeySkip[k] {
			clean[k] = v
		}
	}
	data, _ := json.Marshal(clean)
	sum := sha256.Sum256(data)
	return fmt.Sprintf("egress:%x", sum)
}

// egressGeoFields are the cached egress-probe geo fields merged into nodes
// for collection-level renaming.
var egressGeoFields = []string{"country", "countryCode", "region", "city", "flag"}

// MergeCachedEgressGeo merges cached geo fields into nodes so collection
// renaming can use probed geo data. Pure cache reads — no network I/O, no
// probing inside the download pipeline. geoFromNode in the filter package
// consumes the merged fields.
func MergeCachedEgressGeo(repo *database.CacheRepo, nodes []model.ProxyNode) []model.ProxyNode {
	if repo == nil {
		return nodes
	}
	for _, node := range nodes {
		if node == nil {
			continue
		}
		entry, ok := repo.SafeGet(EgressCacheKey(node))
		if !ok {
			continue
		}
		var cached map[string]any
		if json.Unmarshal([]byte(entry.Content), &cached) != nil {
			continue
		}
		for _, field := range egressGeoFields {
			if v, ok := cached[field]; ok && v != nil {
				node[field] = v
			}
		}
	}
	return nodes
}

// StripEgressGeoFields removes the merged geo fields after renaming so they
// do not leak into rendered subscription output. No parser or filter sets
// these fields natively (they exist on nodes only via the egress merge), so
// stripping is safe.
func StripEgressGeoFields(nodes []model.ProxyNode) {
	for _, node := range nodes {
		if node == nil {
			continue
		}
		for _, field := range egressGeoFields {
			delete(node, field)
		}
	}
}