package main

import (
	"context"
	"fmt"
	"sort"
	"strings"

	"github.com/novox/mesh-controller/internal/catalogue"
	"github.com/novox/mesh-controller/internal/inventory"
)

// A provision whose credential only a person outside the mesh can give (novox/hq ADR 0337, issue 164, issue 165):
// given once for its provider, at the controller's terminal, and sealed in one act to every consumer that binds the
// provision from that provider now. The value is never read back, printed or kept.

// outsideOffer is the provider module's own name when `secret accept <node> <module> <name>` names a provision that
// module offers with a credential issued outside the mesh, and "" when it names anything else (an own secret, or a
// pair with --provider).
func outsideOffer(ctx context.Context, module, name, provider string) (string, error) {
	if provider != "" {
		return "", nil
	}
	open, err := openStores(ctx)
	if err != nil {
		return "", err
	}
	defer open.Close()
	shelf, err := open.inventory.Catalogue(ctx)
	if err != nil {
		return "", err
	}
	if m, known := shelf[module]; known && m.IssuedOutsideOf(name) {
		return module, nil
	}
	return "", nil
}

// offeredOutsideBy is a module that offers the provision with a credential issued outside the mesh, or "".
func offeredOutsideBy(ctx context.Context, provision string) (string, error) {
	open, err := openStores(ctx)
	if err != nil {
		return "", err
	}
	defer open.Close()
	shelf, err := open.inventory.Catalogue(ctx)
	if err != nil {
		return "", err
	}
	module, _ := catalogue.OffersIssuedOutside(shelf, provision)
	return module, nil
}

// consumersFrom is every consumer that binds a provision from one provider now, found by resolving every machine as
// its next send would, and the machines that could not be resolved, with why.
func consumersFrom(ctx context.Context, open *stores, provider, providerModule, provision string) (
	[]inventory.PairEnd, []string, error) {
	nodes, err := open.inventory.Nodes(ctx)
	if err != nil {
		return nil, nil, err
	}
	var out []inventory.PairEnd
	var unresolved []string
	for _, n := range nodes {
		plan, _, err := planFor(ctx, open, n.Name)
		if err != nil {
			unresolved = append(unresolved, fmt.Sprintf("%s: %s", n.Name, oneLine(err.Error())))
			continue
		}
		out = append(out, bindsFrom(plan, n.Name, provider, providerModule, provision)...)
	}
	return out, unresolved, nil
}

// bindsFrom is every consumer on one machine whose resolution answers the provision from that provider. Pure.
func bindsFrom(plan catalogue.Resolution, machine, provider, providerModule, provision string) []inventory.PairEnd {
	var out []inventory.PairEnd
	for _, need := range plan.Needs {
		if need.ByRecord || need.Name != provision || need.From != provider {
			continue
		}
		if need.Module != "" && need.Module != providerModule {
			continue
		}
		out = append(out, inventory.PairEnd{Consumer: machine, ConsumerModule: need.For, Local: need.Local})
	}
	sort.Slice(out, func(i, j int) bool {
		return out[i].ConsumerModule+"\x00"+out[i].Local < out[j].ConsumerModule+"\x00"+out[j].Local
	})
	return out
}

// acceptForProvision gives a provision's credential issued outside the mesh, once for its provider (ADR 0337 §3).
func acceptForProvision(ctx context.Context, provider, providerModule, provision, value string) error {
	open, err := openStores(ctx)
	if err != nil {
		return err
	}
	defer open.Close()
	consumers, unresolved, err := consumersFrom(ctx, open, provider, providerModule, provision)
	if err != nil {
		return err
	}
	accepted, err := open.inventory.AcceptSecretForProvision(ctx, provision, provider, providerModule, value, consumers)
	value = ""
	if err != nil {
		return err
	}
	fmt.Print(acceptedSaid(provider, providerModule, provision, accepted, unresolved))
	if len(accepted.Sealed) == 0 {
		return nil
	}
	if err := sendTo(ctx, open, accepted.Machines); err != nil {
		return fmt.Errorf("%s is sealed and could not be sent: %w; `push %s` sends it", provision, err,
			strings.Join(accepted.Machines, "`, `push "))
	}
	fmt.Printf("  sent %s; each consumer starts again on it\n", strings.Join(accepted.Machines, ", "))
	return nil
}

// acceptedSaid is what one accept for a provider did, in words that never carry the value. Pure.
func acceptedSaid(provider, providerModule, provision string, a inventory.ProvisionAccepted, unresolved []string) string {
	var b strings.Builder
	if len(a.Sealed) == 0 {
		fmt.Fprintf(&b, "%s from %s on %s: no consumer binds it now, so nothing was sealed; a consumer that binds "+
			"later waits for it, and this line given again seals it to every consumer then\n", provision,
			providerModule, provider)
	} else {
		var names []string
		for _, c := range a.Sealed {
			names = append(names, fmt.Sprintf("%s on %s%s", c.ConsumerModule, c.Consumer, asLocal(c.Local)))
		}
		fmt.Fprintf(&b, "%s from %s on %s is given, sealed to %s and to %s\n", provision, providerModule, provider,
			strings.Join(names, ", "), provider)
		fmt.Fprintf(&b, "  the mesh cannot read it back, never makes one of its own for it, and will not rotate it\n")
	}
	for _, c := range a.Unsealable {
		fmt.Fprintf(&b, "  not sealed to %s on %s: no sealing key on that machine; give it again once it has one\n",
			c.ConsumerModule, c.Consumer)
	}
	for _, u := range unresolved {
		fmt.Fprintf(&b, "  not known whether a consumer on %s binds it, which did not resolve; give it again once it does\n", u)
	}
	return b.String()
}