package release

import (
	"encoding/json"
	"os"
	"slices"
	"strings"
)

func replacementReconstruction(g HistoryReconstruction, prior *reconstructionIntent) (HistoryReconstruction, error) {
	raw, err := json.Marshal(prior.Grant)
	if err != nil || reconstructionDigest(raw) != prior.Digest || g.Replaces != prior.Digest || g.Identity != prior.Grant.Identity || g.Revision != prior.Grant.Revision || g.Account != prior.Grant.Account || g.App != prior.Grant.App || g.Operation == prior.Grant.Operation || len(prior.Images) != len(prior.Grant.Hosts)+2 {
		return g, os.ErrPermission
	}
	// Copy signed input before adding restrictive evidence from the old intent.
	g.Hosts = append([]HistoryReconstructionHost(nil), g.Hosts...)
	holds := map[string]HistoryReconstructionHold{}
	for channel, bound := range g.Holds {
		holds[channel] = bound
	}
	g.Holds = holds
	for i := range g.Hosts {
		g.Hosts[i].Refusals = append([]Refusal(nil), g.Hosts[i].Refusals...)
	}
	expected := map[string]bool{rootBakeKey: true, historyAppKey(g.Account, g.App): true}
	for _, old := range prior.Grant.Hosts {
		if !slices.ContainsFunc(g.Hosts, func(h HistoryReconstructionHost) bool { return h.Host == old.Host }) {
			return g, os.ErrPermission
		}
		expected[historyKey(HistoryBinding{Host: old.Host, Account: g.Account, App: g.App})] = true
	}
	for _, im := range prior.Images {
		if !expected[im.Name] {
			return g, os.ErrPermission
		}
		delete(expected, im.Name)
		switch im.Name {
		case historyAppKey(g.Account, g.App):
			var app historyApp
			if strictCanonicalJSON(im.After, &app) != nil || !validHistoryApp(app) || app.Account != g.Account || app.App != g.App {
				return g, os.ErrPermission
			}
		case rootBakeKey:
			var bake rootBakeRecord
			if strictCanonicalJSON(im.After, &bake) != nil || !validRootBake(bake) {
				return g, os.ErrPermission
			}
			if p := bake.Clock.Production[prodKey(g.Account, g.App)]; p != nil {
				g.Production = g.Production || p.WasProduction
				if p.NewestSetAt.After(g.ProductionSetAt) {
					g.ProductionSetAt = p.NewestSetAt
				}
			}
			for key, mem := range bake.Clock.Holds {
				if !strings.HasPrefix(key, holdKeyPrefix(g.Account, g.App)) {
					continue
				}
				channel := strings.TrimPrefix(key, holdKeyPrefix(g.Account, g.App))
				b := g.Holds[channel]
				if mem.Window > b.Window {
					b.Window = mem.Window
				}
				if mem.SetAt.After(b.SetAt) {
					b.SetAt = mem.SetAt
				}
				g.Holds[channel] = b
			}
		default:
			var r historyRecord
			if strictCanonicalJSON(im.After, &r) != nil || !validHistory(r, r.Binding) || r.Binding.Account != g.Account || r.Binding.App != g.App || historyKey(r.Binding) != im.Name || r.Attempt != nil {
				return g, os.ErrPermission
			}
			for i := range g.Hosts {
				if g.Hosts[i].Host != r.Binding.Host {
					continue
				}
				for _, ref := range r.Refusals.Values {
					ref.Recovered = false
					if !slices.Contains(g.Hosts[i].Refusals, ref) {
						g.Hosts[i].Refusals = append(g.Hosts[i].Refusals, ref)
					}
				}
			}
		}
	}
	return g, nil
}