package bind

import (
	"context"
	"fmt"
	"strings"
)

// ZoneFilePath returns the on-pod path of a zone database file.
func ZoneFilePath(zone string) string {
	return fmt.Sprintf("%s/zones/db.%s", DataDir, strings.TrimSuffix(zone, "."))
}

// CatalogFilePath returns the on-pod path of a catalog zone database file.
func CatalogFilePath(zone string) string {
	return fmt.Sprintf("%s/catalog/db.%s", DataDir, strings.TrimSuffix(zone, "."))
}

// ZoneExists reports whether a zone is currently loaded on the pod.
func (e *Executor) ZoneExists(ctx context.Context, namespace, pod, zone, view string) bool {
	args := []string{"zonestatus", zone}
	if view != "" {
		args = append(args, "in", view)
	}
	_, err := e.Rndc(ctx, namespace, pod, args...)
	return err == nil
}

// renderSeedZone renders a minimal loadable zone (SOA + apex NS). nameservers
// are the names published in the apex NS RRset; when empty the in-zone name ns1
// is used. A glue A pointing at primaryIP is emitted only for a nameserver that
// falls inside the zone, because BIND refuses to load a zone whose in-zone NS
// has no address record. Out-of-zone nameservers therefore keep pod IPs out of
// the zone file entirely.
func renderSeedZone(zone, primaryIP string, nameservers []string, serial int64) string {
	origin := dot(zone)
	ns := make([]string, 0, len(nameservers))
	for _, n := range nameservers {
		ns = append(ns, dot(n))
	}
	if len(ns) == 0 {
		ns = []string{"ns1." + origin}
	}
	// Short refresh/retry so a secondary that misses a NOTIFY (e.g. its pod IP
	// changed and the primary's also-notify was briefly stale) still converges
	// in minutes, not the hour a 3600s refresh would impose. minimum is the
	// negative-cache TTL: keep it low so a stale-secondary NXDOMAIN does not
	// stick in downstream resolvers for long. NOTIFY (also-notify on the
	// primary) remains the fast path; these are the fallback.
	var b strings.Builder
	fmt.Fprintf(&b, `$TTL 3600
@ IN SOA %s hostmaster.%s (
    %d ; serial
    300        ; refresh
    60         ; retry
    1209600    ; expire
    60 )       ; minimum
`, ns[0], origin, serial)
	for _, n := range ns {
		fmt.Fprintf(&b, "@ IN NS %s\n", n)
	}
	for _, n := range ns {
		if owner, ok := InZoneOwner(n, zone); ok {
			fmt.Fprintf(&b, "%s IN A %s\n", owner, primaryIP)
		}
	}
	return b.String()
}

// InZoneOwner reports whether name sits inside zone, and if so returns its owner
// name relative to the apex ("@" for the apex itself).
func InZoneOwner(name, zone string) (string, bool) {
	name, origin := dot(name), dot(zone)
	switch {
	case name == origin:
		return "@", true
	case strings.HasSuffix(name, "."+origin):
		return strings.TrimSuffix(name, "."+origin), true
	}
	return "", false
}

// EnsureSeedZone makes path loadable without discarding live data: it probes
// the zone file and journal, moves aside whatever cannot load, and writes a
// skeleton only when there is nothing to preserve. Every caller that needs a
// zone database file on disk goes through here.
func (e *Executor) EnsureSeedZone(ctx context.Context, namespace, pod, zone, path, primaryIP string, nameservers []string) error {
	state, err := e.ZoneDiskState(ctx, namespace, pod, path)
	if err != nil {
		return err
	}
	plan := PlanSeed(state)
	if plan.Blocked != "" {
		return fmt.Errorf("seed zone %s: %s", zone, plan.Blocked)
	}
	if !plan.WriteSeed {
		return e.Quarantine(ctx, namespace, pod, path, plan)
	}
	content := renderSeedZone(zone, primaryIP, nameservers, plan.Serial)
	cmd := []string{"sh", "-c", seedScript(path, plan, len(content))}
	if out, err := e.Exec(ctx, namespace, pod, cmd, content); err != nil {
		return fmt.Errorf("seed zone %s: %w (out: %s)", zone, err, out)
	}
	return nil
}

// seedTempSuffix names the staging file, a sibling of the zone file so the
// install is a same-filesystem rename.
const seedTempSuffix = ".seed-tmp"

// seedScript stages the skeleton, checks it arrived whole, then quarantines and
// installs it in that order. Doing all of it in one exec keeps an interrupted
// seed from leaving the PVC with no zone data, which the next reconcile would
// read as a fresh install and reseed at serial 1; the rename means a torn write
// is never visible at path. shellScript aborts the run at the first failure, so
// no step can install the skeleton over data an earlier step failed to preserve.
func seedScript(path string, plan SeedPlan, size int) string {
	q, tmp := shellQuote(path), shellQuote(path+seedTempSuffix)
	cmds := []string{
		fmt.Sprintf("mkdir -p \"$(dirname %s)\"", q),
		fmt.Sprintf("cat > %s", tmp),
		// A stdin stream cut mid-transfer gives cat a short file and exit 0.
		fmt.Sprintf("n=$(wc -c < %s | tr -d ' \\n')", tmp),
		// Compared as strings: an unmeasurable size is empty, not a number, and
		// a numeric test would exit 2 there and be swallowed by the if.
		fmt.Sprintf("if [ \"$n\" != '%d' ]; then rm -f %s; exit 1; fi", size, tmp),
	}
	if plan.QuarantineZoneFile {
		cmds = append(cmds, moveAside(path, plan.QuarantineSuffix))
	}
	if plan.QuarantineJournal {
		cmds = append(cmds, moveAside(JournalPath(path), plan.QuarantineSuffix))
	}
	return shellScript(append(cmds, fmt.Sprintf("mv -- %s %s", tmp, q))...)
}

// AddCatalogMember registers a member zone in a catalog zone by adding the
// catalog PTR record, so secondaries auto-provision it.
func (e *Executor) AddCatalogMember(ctx context.Context, namespace, pod, catalogZone, memberZone string, creds TSIGCreds) error {
	hash := catalogHash(memberZone)
	owner := fmt.Sprintf("%s.zones.%s", hash, dot(catalogZone))
	updates := []RecordUpdate{{
		FQDN:   owner,
		Type:   "PTR",
		TTL:    3600,
		Values: []string{dot(memberZone)},
	}}
	return e.NSUpdate(ctx, namespace, pod, catalogZone, creds, updates)
}

// RemoveCatalogMember deregisters a member zone from a catalog zone.
func (e *Executor) RemoveCatalogMember(ctx context.Context, namespace, pod, catalogZone, memberZone string, creds TSIGCreds) error {
	hash := catalogHash(memberZone)
	owner := fmt.Sprintf("%s.zones.%s", hash, dot(catalogZone))
	updates := []RecordUpdate{{FQDN: owner, Type: "PTR", Delete: true}}
	return e.NSUpdate(ctx, namespace, pod, catalogZone, creds, updates)
}