package backup

import (
	"context"
	"fmt"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
)

// ABANDONMENT — deciding to give up the old off-site history is a finishable thing (R-241, v0.206.0).
//
// THE PROBLEM THIS SOLVES. `resetOrphanedRepo` renamed the remote store aside and touched neither the
// escrow nor the key, so the hub went on holding a sealed package for a key the box no longer used.
// Shape (c) compares those two, finds them different, and offers recovery — correctly, and for ever.
// A customer who has already said "I do not want the old data" would be asked again at every login.
//
// THE OPERATOR'S RULING (2026-08-07) is that the answer is NOT a "they decided" flag. A flag would
// leave the box in a state that is genuinely wrong (the hub holding a package for a key nobody uses)
// and paper over it. Instead the decision starts a **14-day countdown**, at the end of which the
// set-aside store and the sealed package that protects it are removed TOGETHER — after which there is
// nothing left to compare and nothing left to ask about. **Fix the state, do not remember that it is
// wrong.**
//
// THE GRACE IS REAL, NOT DECORATIVE. The recovery offer stays reachable for the whole window; that is
// the change-of-mind path (Scenario G). A grace period during which recovery is impossible would be
// theatre.

// abandonGraceDays is the countdown the operator set. Reminders fire at 5, 3 and 1 days (see
// AbandonRemindAtDays) — visible, reversible, and running out in public.
const abandonGraceDays = 14

// AbandonGraceDays is the exported grace, for the customer-facing copy. The confirmation screen must
// state the SAME number the countdown uses — a literal typed into prose is how a promise drifts away
// from the code that keeps it.
const AbandonGraceDays = abandonGraceDays

// AbandonRemindAtDays are the remaining-day marks at which the abandoning box reminds the customer.
// Descending, so the surface can pick the first one that has been reached.
var AbandonRemindAtDays = []int{5, 3, 1}

// abandonNow is the countdown's clock seam. Tests inject; nil → time.Now. It exists so the terminal
// step can be driven deterministically — §7.4 forbids shortening a live timer to watch it fire,
// because that is how an irreversible step gets tested once and regretted once.
func (m *Manager) abandonNow() time.Time {
	if m.offboxNow != nil {
		return m.offboxNow()
	}
	return time.Now()
}

// SetOffboxClock injects the abandonment clock (tests only).
func (m *Manager) SetOffboxClock(fn func() time.Time) { m.offboxNow = fn }

// startAbandonCountdown records the decision and the date the terminal step will run. Called by
// resetOrphanedRepo AFTER the move-aside has succeeded — a countdown started before the store has
// actually moved would count down to deleting a path that does not exist.
func (m *Manager) startAbandonCountdown(setAsidePath string) {
	now := m.abandonNow().UTC()
	due := now.AddDate(0, 0, abandonGraceDays)
	if err := m.settings.UpdateOffboxStatus(func(o *settings.OffboxTarget) {
		o.AbandonStartedAt = now.Format(time.RFC3339)
		o.AbandonAt = due.Format(time.RFC3339)
		o.AbandonRepoPath = setAsidePath
		o.AbandonPurgeRequested = false
	}); err != nil {
		m.logger.Printf("[WARN] [offbox] could not record the abandonment countdown: %v", err)
		return
	}
	m.logger.Printf("[INFO] [offbox] abandonment countdown started: the set-aside history at %s and the hub's sealed package "+
		"are removed together on %s (%d days). The recovery screen stays reachable until then.",
		setAsidePath, due.Format("2006-01-02"), abandonGraceDays)
}

// AbandonState is the surface's read model. Zero value = nothing in progress.
type AbandonState struct {
	Active         bool      // a countdown is running
	StartedAt      time.Time //
	DueAt          time.Time // when the terminal step runs
	DaysLeft       int       // ceiling, so "0 days left" only ever means "today"
	RepoPath       string    // the set-aside store awaiting deletion
	PurgeRequested bool      // the store is gone; awaiting the hub to drop the sealed package
}

// AbandonStatus reports the countdown for the UI and the report. It never mutates.
func (m *Manager) AbandonStatus() AbandonState {
	t := m.settings.GetOffboxTarget()
	if t == nil {
		return AbandonState{}
	}
	st := AbandonState{RepoPath: t.AbandonRepoPath, PurgeRequested: t.AbandonPurgeRequested}
	if t.AbandonAt == "" {
		return st
	}
	due, err := time.Parse(time.RFC3339, t.AbandonAt)
	if err != nil {
		// A malformed stamp must not silently mean "never due" — that would strand the store for ever
		// with a countdown the customer can see and nothing behind it.
		m.logger.Printf("[WARN] [offbox] abandonment due-date is unparseable (%q) — treating the countdown as NOT running: %v", t.AbandonAt, err)
		return st
	}
	st.Active, st.DueAt = true, due
	if s, serr := time.Parse(time.RFC3339, t.AbandonStartedAt); serr == nil {
		st.StartedAt = s
	}
	// Ceiling: a countdown with 30 minutes left says "1 day", never "0". Zero is reserved for due.
	remaining := due.Sub(m.abandonNow())
	if remaining <= 0 {
		st.DaysLeft = 0
	} else {
		st.DaysLeft = int((remaining + 24*time.Hour - time.Nanosecond) / (24 * time.Hour))
	}
	return st
}

// CancelAbandon stops a running countdown — the change-of-mind path (Scenario G). Called when a
// recovery succeeds: the customer has their code after all, and the history they were about to give
// up is exactly what the code opens.
//
// It clears the schedule but KEEPS AbandonRepoPath, so the set-aside store remains nameable on the
// backups page. Nothing has been deleted at this point by construction — the terminal step is the
// only thing that deletes, and it has not run.
func (m *Manager) CancelAbandon(reason string) {
	t := m.settings.GetOffboxTarget()
	if t == nil || (t.AbandonAt == "" && !t.AbandonPurgeRequested) {
		return // nothing running — silent, so a healthy recovery does not log about a countdown
	}
	if err := m.settings.UpdateOffboxStatus(func(o *settings.OffboxTarget) {
		o.AbandonStartedAt, o.AbandonAt = "", ""
		o.AbandonPurgeRequested = false
	}); err != nil {
		m.logger.Printf("[WARN] [offbox] could not cancel the abandonment countdown: %v", err)
		return
	}
	m.logger.Printf("[INFO] [offbox] abandonment countdown CANCELLED (%s) — the set-aside history at %s is kept and nothing was deleted", reason, t.AbandonRepoPath)
}

// AbandonSweep is the daily terminal step. It is the ONLY thing in the product that deletes a
// customer's off-site history, and it does so on a date the customer was shown.
//
// ⚠ IT REMOVES BOTH HALVES OR NEITHER — Scenario F. The set-aside store and the sealed package that
// protects it are the two halves of one thing; removing only the store leaves the hub holding a
// package for a key that opens nothing, and removing only the package leaves ciphertext nobody can
// ever decrypt. Either is a state that asks a question nobody can answer.
//
// The two halves cannot be made atomic across two machines, so this is a two-phase commit with the
// STORE FIRST and a durable marker: delete the remote store, record AbandonPurgeRequested, and keep
// declaring it in the report until the hub's ACK stops reporting a superseded package. A crash
// between the two leaves the marker set and the next sweep re-declares — it never leaves the pair
// half-removed and silent.
//
// Returns (deleted, err). deleted=false with err=nil is the normal "nothing due" case.
func (m *Manager) AbandonSweep(ctx context.Context) (bool, error) {
	st := m.AbandonStatus()
	// Phase 2 outstanding: the store is gone, the hub has not confirmed. Re-declare and wait.
	if st.PurgeRequested {
		m.logger.Printf("[DEBUG] [offbox] abandonment: the set-aside store is deleted; awaiting the hub to drop the sealed package")
		return false, nil
	}
	if !st.Active || st.DueAt.After(m.abandonNow()) {
		return false, nil // not due — quiet by construction on every healthy box
	}
	t := m.settings.GetOffboxTarget()
	if t == nil || t.AbandonRepoPath == "" {
		m.logger.Printf("[WARN] [offbox] abandonment is due but no set-aside path is recorded — nothing deleted; clearing the countdown so it does not retry for ever")
		m.CancelAbandon("no set-aside path recorded")
		return false, fmt.Errorf("abandonment due with no recorded path")
	}
	port := t.Port
	if port == 0 {
		port = 22
	}
	m.logger.Printf("[WARN] [offbox] abandonment DUE — deleting the set-aside off-site history at %s (chosen by the customer on %s; this is irreversible)",
		t.AbandonRepoPath, st.StartedAt.Format("2006-01-02"))
	out, err := m.sshRunner()(ctx, t.Host, t.User, port, m.offboxKeyPath(), m.offboxKnownHosts(),
		"rm -rf "+shellQuote(t.AbandonRepoPath))
	if err != nil {
		// NOT cleared: a transport failure must retry tomorrow, not silently abandon the abandonment.
		m.logger.Printf("[ERROR] [offbox] abandonment: deleting the set-aside history failed — the countdown stays due and retries: %v: %s", err, truncate(out))
		return false, fmt.Errorf("delete set-aside history: %w", err)
	}
	// Phase 1 done. Record it durably BEFORE anything else, so a crash here re-declares rather than
	// forgetting that the store is already gone.
	if uerr := m.settings.UpdateOffboxStatus(func(o *settings.OffboxTarget) {
		o.AbandonPurgeRequested = true
		o.AbandonAt = "" // the schedule has fired; the marker now drives the rest
	}); uerr != nil {
		m.logger.Printf("[ERROR] [offbox] abandonment: the store was deleted but the marker could not be saved — the hub's package may outlive it: %v", uerr)
		return true, uerr
	}
	m.logger.Printf("[INFO] [offbox] abandonment: set-aside history deleted; requesting the hub to drop the sealed package that protected it")
	if m.offboxOrphanEvent != nil {
		m.offboxOrphanEvent("offbox_abandon_completed", t.AbandonRepoPath)
	}
	return true, nil
}

// ClearAbandonPurgeIfConfirmed closes the two-phase commit: once the hub's ACK stops reporting a
// superseded package, both halves are gone and the abandonment is finished. Called from the ACK path.
//
// This is what makes §2.1 work without a "they decided" flag: afterwards the hub holds a package for
// the key the box is actually using (or none at all), shape (c) has nothing to compare, and the
// recovery offer falls silent on its own — because the state is right, not because something is
// remembering that it once was not.
func (m *Manager) ClearAbandonPurgeIfConfirmed(supersededPresent bool) {
	t := m.settings.GetOffboxTarget()
	if t == nil || !t.AbandonPurgeRequested || supersededPresent {
		return
	}
	if err := m.settings.UpdateOffboxStatus(func(o *settings.OffboxTarget) {
		o.AbandonPurgeRequested = false
		o.AbandonRepoPath = ""
		o.AbandonStartedAt = ""
		o.OrphanedRenamedTo = ""
	}); err != nil {
		m.logger.Printf("[WARN] [offbox] could not close out the abandonment: %v", err)
		return
	}
	m.logger.Printf("[INFO] [offbox] abandonment COMPLETE — the set-aside history and the sealed package that protected it are both gone; nothing further to ask about")
}

// ── OPERATOR CONTROL (§7.5) ─────────────────────────────────────────────────────────────────────
//
// The automatic 30-day abandonment is deliberately NOT built (see R-245). What IS built is the path
// that actually happens: **the customer gets in touch.** Someone who cannot find their recovery code
// rings support, and support needs something to press — either "give them longer" or "stop it".
//
// Both live on the controller CLI rather than in the customer UI, deliberately: extending a deletion
// the customer asked for is an operator judgement, not a self-service button, and a customer who
// wants it stopped already has the self-service route — they recover with their code, which cancels
// it (Scenario G).

// ExtendAbandon pushes the terminal step out by `days` from NOW. Returns the new due date.
//
// It refuses when no countdown is running: extending nothing would print a reassuring date for a
// deletion that was never scheduled, which is the kind of comfort this project keeps removing.
func (m *Manager) ExtendAbandon(days int) (time.Time, error) {
	if days <= 0 {
		return time.Time{}, fmt.Errorf("the extension must be a positive number of days")
	}
	st := m.AbandonStatus()
	if !st.Active {
		if st.PurgeRequested {
			return time.Time{}, fmt.Errorf("too late: the set-aside history has already been deleted and only the sealed package is still being removed")
		}
		return time.Time{}, fmt.Errorf("no abandonment countdown is running on this box — nothing to extend")
	}
	due := m.abandonNow().UTC().AddDate(0, 0, days)
	if err := m.settings.UpdateOffboxStatus(func(o *settings.OffboxTarget) {
		o.AbandonAt = due.Format(time.RFC3339)
	}); err != nil {
		return time.Time{}, fmt.Errorf("record the extension: %w", err)
	}
	m.logger.Printf("[WARN] [offbox] abandonment EXTENDED by an operator: the set-aside history at %s is now deleted on %s (was %s)",
		st.RepoPath, due.Format("2006-01-02"), st.DueAt.Format("2006-01-02"))
	return due, nil
}

// StopAbandon cancels the countdown outright — the operator's version of Scenario G, for the
// customer who telephoned instead of finding their code. The set-aside history is kept and nothing
// is deleted; it is `CancelAbandon` with an operator's reason and a refusal when nothing is running,
// so an operator never gets a silent no-op they might read as success.
func (m *Manager) StopAbandon() error {
	st := m.AbandonStatus()
	if !st.Active {
		if st.PurgeRequested {
			return fmt.Errorf("too late: the set-aside history has already been deleted")
		}
		return fmt.Errorf("no abandonment countdown is running on this box — nothing to stop")
	}
	m.CancelAbandon("stopped by an operator")
	return nil
}