package inventory

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/jackc/pgx/v5"
)

// A value given by hand lives only until the module's first good start (novox/hq ADR 0228).
//
// **A person gives a module's own secret for one reason**: to adopt something already running that
// holds that value. A module the mesh installs fresh needs none — the mesh makes it. So for a secret
// the mesh may make (catalogue.OwnSecret.MeshMayMake: read at start, issued by nobody outside), a
// given value is kept until the module has started under the mesh on it, and then replaced with one
// the mesh makes, sealed and sent like any other. Nothing a person handled is left in force.
//
// What stays as given: a value an outside party issued (an API key, a bot token, a licence), which
// no value of the mesh's would replace; a value a module applies to a backend, until the staged
// rotation exists (ADR 0114); and a value given before this rule, which waits for a person to ask
// `secret rotate` — the mesh does not decide for them that what was given long ago is used nowhere
// else.

// AcceptGivenSecret is `secret accept` for a module's own secret: the value a person gave, sealed as
// AcceptSecretForModule seals it, and — for a secret the mesh may make — marked to be replaced after
// the module's first good start. It answers whether it was so marked.
//
// **Only the person's path marks.** The mesh's own code accepts values too — a bus account it
// issued, the controller's bus address — and those are the mesh's word to a broker, which a fresh
// random value would break; they go through AcceptSecretForModule and are never marked.
func (i *Inventory) AcceptGivenSecret(ctx context.Context, node, module, name, value string) (untilStart bool, err error) {
	return i.acceptOwn(ctx, node, module, name, value, true)
}

// OwnSecretOrigin is where a module's own secret on a machine came from — OriginMade or
// OriginAccepted — and when it was made or given; empty for one it does not hold yet.
func (i *Inventory) OwnSecretOrigin(ctx context.Context, node, module, name string) (string, time.Time, error) {
	record, err := i.NodeByName(ctx, node)
	if err != nil {
		return "", time.Time{}, err
	}
	var origin string
	var at time.Time
	err = i.store.Pool().QueryRow(ctx,
		`select origin, made_at from module_secret where node = $1 and module = $2 and name = $3`,
		record.ID, module, name).Scan(&origin, &at)
	if errors.Is(err, pgx.ErrNoRows) {
		return "", time.Time{}, nil
	}
	return origin, at, err
}

// givenAgo is ", given <date>, N days ago" for a refusal about a value given to the mesh, and empty
// when the mesh holds none: how old an outside party's key is, said where a person learns it cannot
// be rotated by the mesh.
func (i *Inventory) givenAgo(ctx context.Context, nodeID any, module, name string) string {
	var origin string
	var at time.Time
	err := i.store.Pool().QueryRow(ctx,
		`select origin, made_at from module_secret where node = $1 and module = $2 and name = $3`,
		nodeID, module, name).Scan(&origin, &at)
	if err != nil || origin != OriginAccepted {
		return ""
	}
	return fmt.Sprintf("; the value held was given %s, %d day(s) ago",
		at.UTC().Format("2006-01-02"), int(time.Since(at).Hours()/24))
}

// GivenReplaced is one given value the mesh replaced after its module's first good start.
type GivenReplaced struct {
	Module, Name string
	// Given is when the replaced value was given.
	Given time.Time
	// Machines are the machines to send so the module, and every holder of a shared credential,
	// starts again on the new value.
	Machines []string
}

// ReplaceGivenAfterStart replaces every given value on a machine whose module has now started well
// under the mesh on it (novox/hq ADR 0228), and answers what it replaced; the caller sends the
// machines each names.
//
// **The signal is the machine's clean report of the declaration it was last sent** — every resource
// applied, nothing failed or refused — **when that declaration was sent after the value was given**,
// so it is the start on the given value that counts, not an older one. On an adopted machine the
// module must also be taken: until then the mesh runs nothing of it, and nothing has started under
// the mesh. Each row is claimed by clearing its mark before it is remade, so two reports arriving
// together replace a value once; a remake that fails puts the mark back, and the next good report
// tries again.
func (i *Inventory) ReplaceGivenAfterStart(ctx context.Context, node, declared string) ([]GivenReplaced, error) {
	if declared == "" {
		return nil, nil
	}
	rows, err := i.store.Pool().Query(ctx,
		`select s.node, s.module, s.name, s.replace_after_start
		   from module_secret s
		   join node n on n.id = s.node
		   join assignment a on a.node = s.node and a.module = s.module
		  where n.name = $1 and n.sent = $2 and n.sent_at > s.replace_after_start
		    and s.origin = 'accepted' and s.replace_after_start is not null
		    and (not n.adopted or exists (select 1 from taken t where t.node = s.node and t.module = s.module))
		  order by s.module, s.name`, node, declared)
	if err != nil {
		return nil, err
	}
	type due struct {
		nodeID       any
		module, name string
		given        time.Time
	}
	var dues []due
	for rows.Next() {
		var d due
		if err := rows.Scan(&d.nodeID, &d.module, &d.name, &d.given); err != nil {
			rows.Close()
			return nil, err
		}
		dues = append(dues, d)
	}
	rows.Close()
	if err := rows.Err(); err != nil {
		return nil, err
	}
	if len(dues) == 0 {
		return nil, nil
	}
	key, err := i.SealingKeyOf(ctx, node)
	if err != nil {
		return nil, err
	}
	if key == "" {
		return nil, fmt.Errorf("%s has no sealing key, so the given values it holds cannot be replaced", node)
	}

	var out []GivenReplaced
	var errs []error
	for _, d := range dues {
		claimed, err := i.store.Pool().Exec(ctx,
			`update module_secret set replace_after_start = null
			  where node = $1 and module = $2 and name = $3 and origin = 'accepted'
			    and replace_after_start = $4`, d.nodeID, d.module, d.name, d.given)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		if claimed.RowsAffected() != 1 {
			continue // replaced by another report, or given again since
		}
		m, err := i.declared(ctx, d.module)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		// The definition is asked again now, not only when the value was given: one that has since
		// said the value is an outside party's, or applied, keeps it as given, and the mark stays gone.
		if own, ok := m.OwnSecrets[d.name]; !ok || !own.MeshMayMake() {
			continue
		}
		if err := i.remakeOwn(ctx, d.nodeID, key, m, d.module, d.name); err != nil {
			if _, back := i.store.Pool().Exec(ctx,
				`update module_secret set replace_after_start = $4
				  where node = $1 and module = $2 and name = $3 and origin = 'accepted'
				    and replace_after_start is null`, d.nodeID, d.module, d.name, d.given); back != nil {
				err = errors.Join(err, fmt.Errorf("and its mark could not be put back: %w", back))
			}
			errs = append(errs, fmt.Errorf("%s's given %q on %s was not replaced: %w", d.module, d.name, node, err))
			continue
		}
		machines, err := i.SharedHolders(ctx, node, d.module, d.name)
		if err != nil {
			errs = append(errs, err)
		}
		if len(machines) == 0 {
			machines = []string{node}
		}
		out = append(out, GivenReplaced{Module: d.module, Name: d.name, Given: d.given, Machines: machines})
	}
	return out, errors.Join(errs...)
}