package stacks

import (
	"path/filepath"
	"regexp"
	"strings"
	"time"
)

// ── Exact image fingerprints on the box (`09` §6.4 part 6, box half; §3 decision 17; v0.269.0) ────
//
// The catalog records, per ladder entry, the registry digest of every `to` ref at the moment the step was
// tested (`scripts/image_digest.py`). The box:
//
//  1. RENDERS `name:tag@sha256:…` into the compose file it runs whenever the entry for exactly those refs
//     carries a digest — so a pull fetches the TESTED image, not whatever the tag points at today.
//     Docker and Compose accept the form and refuse a digest that does not exist (measured on 9202,
//     2026-09-23, `audits/update-rulings-2026-09-23/70-…`).
//  2. Keeps every PIN and every RECORD digest-free: ParseComposeImages strips `@…`, and the installed
//     record's Ref is stripped too (its Digest is a field of its own). One strip at each door, so the
//     pin, the ladder, the badge and the syncer all compare plain `name:tag`.
//  3. Reads the badge from the TESTED digest only — never a registry query (`09` §8.1): same tag, a
//     different installed digest, and a catalog test NEWER than the install → „Frissítés elérhető".

var digestRe = regexp.MustCompile(`^sha256:[0-9a-f]{64}$`)

// StripDigest removes a `@sha256:…` suffix from an image reference.
func StripDigest(ref string) string {
	if at := strings.LastIndex(ref, "@"); at >= 0 {
		return ref[:at]
	}
	return ref
}

var serviceLineRe = regexp.MustCompile(`^  ([A-Za-z0-9_-]+):\s*$`)
var imageLineRe = regexp.MustCompile(`^(\s+image:\s*)["']?([^\s"'#]+)["']?(.*)$`)

// renderDigests rewrites each service's own `image:` line to `ref@digest` when digests carries a valid
// one for that service. Line-based (the catalog's own reading, `ladder.images_in`), so comments and
// every other byte are kept. A service with no valid digest keeps its line.
func renderDigests(compose []byte, digests map[string]string) []byte {
	if len(digests) == 0 {
		return compose
	}
	lines := strings.Split(string(compose), "\n")
	svc := ""
	done := map[string]bool{}
	inServices := false
	for i, l := range lines {
		if strings.HasPrefix(l, "services:") {
			inServices = true
			continue
		}
		if l != "" && !strings.HasPrefix(l, " ") && !strings.HasPrefix(l, "#") {
			inServices = false
		}
		if !inServices {
			continue
		}
		if m := serviceLineRe.FindStringSubmatch(l); m != nil {
			svc = m[1]
			continue
		}
		m := imageLineRe.FindStringSubmatch(l)
		if m == nil || svc == "" || done[svc] {
			continue
		}
		d := digests[svc]
		if !digestRe.MatchString(d) {
			continue
		}
		lines[i] = m[1] + StripDigest(m[2]) + "@" + d + m[3]
		done[svc] = true
	}
	return []byte(strings.Join(lines, "\n"))
}

// ladderEntryFor returns the NEWEST ladder entry whose `to` is exactly these (digest-free) refs.
func ladderEntryFor(templateDir string, refs map[string]string) (LadderEntry, bool) {
	ladder, err := LoadLadder(filepath.Join(templateDir, ".felhom.yml"))
	if err != nil {
		return LadderEntry{}, false
	}
	for i := len(ladder) - 1; i >= 0; i-- {
		if sameRefs(ladder[i].To, refs) {
			return ladder[i], true
		}
	}
	return LadderEntry{}, false
}

// RenderWithLadderDigests is what the syncer and the update write: the compose bytes with the tested
// digests of the ladder entry for exactly its refs. No entry, or no digest → the bytes unchanged.
func RenderWithLadderDigests(templateDir string, compose []byte) []byte {
	refs, err := parseComposeImagesBytes(compose)
	if err != nil || len(refs) == 0 {
		return compose
	}
	e, ok := ladderEntryFor(templateDir, refs)
	if !ok {
		return compose
	}
	return renderDigests(compose, e.Digest)
}

// catalogTestedDigests is the badge's input: the tested digest per service of the catalog's current
// refs, and when that test ran. Empty when the ladder has no entry for them.
func catalogTestedDigests(templateDir string, catalogRefs map[string]string) (map[string]string, time.Time) {
	e, ok := ladderEntryFor(templateDir, catalogRefs)
	if !ok {
		return nil, time.Time{}
	}
	t, _ := time.Parse(time.RFC3339, e.TestedAt)
	return e.Digest, t
}