package main

import (
	"context"
	"fmt"
	"io"
	"os"
	"strings"

	"git.novox.be/novox/mesh-sdk/go/catalogue"

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

// processUser is the bus user of one process of a module on a node (novox/hq ADR 0436 §1).
func processUser(node, module, process string) string {
	return broker.Principal{Kind: broker.KindProcess, Node: node, Module: module, Process: process}.Username()
}

// processAccountWarning is the warning line for the own secret broker-<process id> of a process that declares bus
// when nobody issued its account (novox/hq ADR 0436 §2, issue 1226): "" for any other secret and for an issued
// account. The send goes on with the stand-in until the composition leaves the module off (issue 1753), so the
// line is the only loud thing about it.
func processAccountWarning(m catalogue.Manifest, node, secret string, minted []string) string {
	id, isProcess := strings.CutPrefix(secret, "broker-")
	if !isProcess {
		return ""
	}
	if _, declared := m.ProcessBuses()[id]; !declared {
		return ""
	}
	user := processUser(node, m.Module, id)
	for _, u := range minted {
		if u == user {
			return ""
		}
	}
	return fmt.Sprintf("%s/%s process %s: its bus account is not issued — mesh-controller.issue %s %s",
		node, m.Module, id, node, m.Module)
}

// sayWarning writes a line where the compose's other warnings go: the act's answer when it carries a writer,
// else the controller's journal.
func sayWarning(ctx context.Context, line string) {
	var w io.Writer = os.Stderr
	if lw, ok := ctx.Value(leftOutKey{}).(io.Writer); ok {
		w = lw
	}
	fmt.Fprintln(w, line)
}

// processAccountsMissing is each process of m that declares bus and whose account is not minted yet on node.
func processAccountsMissing(m catalogue.Manifest, node string, minted []string) []broker.ProcessPrincipal {
	have := map[string]bool{}
	for _, u := range minted {
		have[u] = true
	}
	var out []broker.ProcessPrincipal
	for _, pr := range inventory.ProcessesOf(m) {
		if !have[processUser(node, m.Module, pr.Process)] {
			out = append(out, pr)
		}
	}
	return out
}

// issueMissingProcessAccounts issues the accounts of m's bus processes on node that are not minted, and no
// other: an account already issued is rotated on purpose, never by a later delivery or assignment (issue 1226).
// It says what it issued, one line, and nothing when nothing was missing.
func issueMissingProcessAccounts(ctx context.Context, inv *inventory.Inventory, m catalogue.Manifest, node string) (string, error) {
	if len(m.ProcessBuses()) == 0 || mayIssue(m) != nil {
		return "", nil
	}
	minted, err := inv.BusMinted(ctx)
	if err != nil {
		return "", err
	}
	missing := processAccountsMissing(m, node, minted)
	if len(missing) == 0 {
		return "", nil
	}
	known, err := broker.FromEnvironment()
	if err != nil {
		return "", fmt.Errorf("cannot deliver a credential without knowing where the bus is: %w", err)
	}
	reachable, err := brokerReachableAt(ctx, inv, known, node)
	if err != nil {
		return "", err
	}
	busAddress, err := broker.BusAddress()
	if err != nil {
		busAddress = ""
	}
	var ids []string
	for _, pr := range missing {
		if err := issueProcess(ctx, inv, m, pr, node, busAddress, known, reachable); err != nil {
			return "", err
		}
		ids = append(ids, pr.Process)
	}
	return fmt.Sprintf("its process account(s) %s issued and sealed to %s, and arrive with the push",
		strings.Join(ids, ", "), node), nil
}

// issueGainedProcessAccounts runs after a module's new definition is registered: on each machine assigned it, the
// accounts of its bus processes not yet minted are issued, so a process a delivery adds is not pushed with a
// random stand-in (issue 1226). Never fatal: the build worked and the module is registered, so a failure is said,
// and the push refuses the module until `mesh-controller.issue` is run.
func issueGainedProcessAccounts(ctx context.Context, inv *inventory.Inventory, m catalogue.Manifest) {
	if len(m.ProcessBuses()) == 0 {
		return
	}
	nodes, err := inv.Running(ctx, m.Module)
	if err != nil {
		fmt.Printf("%s: its machines are not read to issue its process accounts: %v\n", m.Module, err)
		return
	}
	for _, node := range nodes {
		line, err := issueMissingProcessAccounts(ctx, inv, m, node)
		if err != nil {
			fmt.Printf("%s on %s: its process accounts are not issued (%v): `mesh-controller.issue %s %s` first\n",
				m.Module, node, err, node, m.Module)
			continue
		}
		if line != "" {
			fmt.Printf("%s on %s: %s\n", m.Module, node, line)
		}
	}
}