package geoip

import (
	"encoding/json"
	"fmt"
	"strings"
	"time"
)

// FeedSpec is one supported feed (spec §10.1): the env name, the database
// type it must deliver, and its provider.
type FeedSpec struct{ Name, Type, Provider string }

var feeds = map[string]FeedSpec{
	"dbip-city-lite":    {"dbip-city-lite", "DBIP-City-Lite", "dbip"},
	"dbip-country-lite": {"dbip-country-lite", "DBIP-Country-Lite", "dbip"},
	"geolite2-city":     {"geolite2-city", "GeoLite2-City", "maxmind"},
	"geolite2-country":  {"geolite2-country", "GeoLite2-Country", "maxmind"},
	// The paid upgrade (Paul, 2026-10-07): MaxMind's commercial databases,
	// the same download API and credentials. Not GeoLite2, so no D1 expiry,
	// and no attribution the platform knows of: the operator's MaxMind
	// licence governs.
	"geoip2-city":    {"geoip2-city", "GeoIP2-City", "maxmind"},
	"geoip2-country": {"geoip2-country", "GeoIP2-Country", "maxmind"},
}

// ParseFeed resolves CONSOLE_GEOIP_FEED.
func ParseFeed(name string) (FeedSpec, bool) {
	s, ok := feeds[strings.TrimSpace(name)]
	return s, ok
}

// DBIPURL is the month's DB-IP Lite download (spec §10.2).
func DBIPURL(base string, spec FeedSpec, month time.Time) string {
	if base == "" {
		base = "https://download.db-ip.com"
	}
	kind := strings.TrimSuffix(strings.TrimPrefix(spec.Name, "dbip-"), "-lite") // city | country
	return fmt.Sprintf("%s/free/dbip-%s-lite-%s.mmdb.gz", base, kind, month.UTC().Format("2006-01"))
}

// MaxMindURL is the GeoLite2 permalink; suffix is "tar.gz" or "tar.gz.sha256".
func MaxMindURL(base string, spec FeedSpec, suffix string) string {
	if base == "" {
		base = "https://download.maxmind.com"
	}
	return fmt.Sprintf("%s/geoip/databases/%s/download?suffix=%s", base, spec.Type, suffix)
}

// FeedStatus is control/geoip/feed.json, written by the console after every
// check (spec §10.4). Box names the console's box: the one box whose mirror
// raises the feed reason, so it fires once.
type FeedStatus struct {
	V                   int       `json:"v"`
	Feed                string    `json:"feed"`
	Box                 string    `json:"box"`
	LastCheck           time.Time `json:"last_check"`
	LastSuccess         time.Time `json:"last_success,omitempty"`
	LastEdition         string    `json:"last_edition,omitempty"`
	ConsecutiveFailures int       `json:"consecutive_failures"`
	LastFailure         string    `json:"last_failure,omitempty"` // a fixed category, never an error text
	ConsecutiveNotFound int       `json:"consecutive_not_found"`
}

// FeedNotFoundAlert is how many failing checks in a row raise the alert.
const FeedNotFoundAlert = 7

// ParseFeedStatus decodes feed.json.
func ParseFeedStatus(raw []byte) (FeedStatus, error) {
	var s FeedStatus
	if err := json.Unmarshal(raw, &s); err != nil {
		return FeedStatus{}, fmt.Errorf("geoip feed status: %w", err)
	}
	if s.V != 1 {
		return FeedStatus{}, fmt.Errorf("geoip feed status: version %d: %w", s.V, ErrUnknownVersion)
	}
	return s, nil
}

// Failing is the alert's feed reason: 7 failed or not-found checks in a row.
func (s FeedStatus) Failing() bool {
	return s.ConsecutiveFailures >= FeedNotFoundAlert || s.ConsecutiveNotFound >= FeedNotFoundAlert
}