package versions

import (
	"encoding/json"
	"fmt"
	"sort"
	"strings"
	"time"
)

// **A publish that ends badly is loud** (design 51 *Health and conditions*; review round 1): the builder raises the
// finding publish-refused when a holder says refused, and publish-unanswered when a version it built and numbered is
// neither published nor refused within PublishBound. Each is about the name, so a later published of any version of it
// clears both. A seat's outcome that does not read is the finding seat-outcome-unread about the seat, cleared by its
// next outcome that reads.
//
// The bound is a key of the builder's state bounds per version (PublishBoundKey), written with its own time to live
// when the build is done and the version is still numbered, deleted at the holder's word; the bus's marker of its end,
// heard on the watch, is what raises publish-unanswered while the version is still numbered. No timer.
const (
	// BoundsState is the builder's state of its expiring keys, each with its own time to live: a publish's bound
	// (PublishBoundKey) and a node's seven days holding the old form's window (OldFormBoundKey). Its end, the bus's
	// marker heard on the watch, is what acts.
	BoundsState  = "bounds"
	BoundsBucket = "mesh-delivery-builder_bounds"
	// PublishBound is the build module's own wait for the holder's word (design 51 *How a publish ends*: at most
	// 10 minutes), so a version unanswered past it is one the holder never answered.
	PublishBound = 10 * time.Minute

	PublishRefused    = "publish-refused"
	PublishUnanswered = "publish-unanswered"
	SeatOutcomeUnread = "seat-outcome-unread"
)

// The prefixes of the keys of BoundsState.
const (
	publishBoundPrefix = "publish."
	oldFormBoundPrefix = "old-form."
)

// PublishBoundKey is the bound of name's version: `publish.<versions key>`.
func PublishBoundKey(name, version string) string { return publishBoundPrefix + Key(name, version) }

// OldFormBoundKey is the bound of node's seven days holding the old form's window: `old-form.<node>`.
func OldFormBoundKey(node string) string { return oldFormBoundPrefix + EscapeToken(node) }

// PublishBoundOf is the versions key a publish's bound names, and whether key is one; a key that is no publish's
// bound is an old form's (IsOldFormBound) or nothing the builder wrote.
func PublishBoundOf(key string) (string, bool) { return strings.CutPrefix(key, publishBoundPrefix) }

// IsOldFormBound says key is a node's bound of the old form's window: its end steps the window, which raises the
// finding for every node past FindingAfter.
func IsOldFormBound(key string) bool { return strings.HasPrefix(key, oldFormBoundPrefix) }

// BoundsTool is builder_bounds: every key of BoundsState, what it bounds and when it ends.
const BoundsTool = "builder_bounds"

// BoundsDescription is builder_bounds' description.
const BoundsDescription = "The builder's expiring keys, its state " + BoundsState + " (design 51 *Health and conditions*): each key with what it " +
	"bounds (a version's publish, whose end unanswered is the finding " + PublishUnanswered + "; or a node's seven days holding the old " +
	"form's window, whose end is the finding " + OldFormHeld + "), when it ends, and how long is left. The bus ends each key by its own time to live."

// Bound is a key's value in BoundsState: what it bounds, in plain words, and when it ends.
type Bound struct {
	Bounds string    `json:"bounds"`
	Ends   time.Time `json:"ends"`
}

// EncodeBound is a Bound's bytes.
func EncodeBound(what string, ends time.Time) []byte {
	raw, _ := json.Marshal(Bound{Bounds: what, Ends: ends.UTC()})
	return raw
}

// BoundRow is one row of builder_bounds.
type BoundRow struct {
	Key    string    `json:"key"`
	Bounds string    `json:"bounds"`
	Ends   time.Time `json:"ends,omitzero"`
	Left   string    `json:"left,omitempty"`
}

// AnswerBounds is builder_bounds: every key, sorted, with what it bounds and when it ends; a value that does not read
// says so in bounds.
func AnswerBounds(r Reader, now time.Time) ([]BoundRow, error) {
	keys, err := r.Keys()
	if err != nil {
		return nil, fmt.Errorf("the state %s cannot be listed: %w", BoundsState, err)
	}
	sort.Strings(keys)
	out := []BoundRow{}
	for _, k := range keys {
		raw, ok, err := r.Get(k)
		if err != nil || !ok {
			continue
		}
		var b Bound
		row := BoundRow{Key: k}
		if json.Unmarshal(raw, &b) != nil || b.Bounds == "" {
			row.Bounds = "a value that does not read: " + string(raw)
		} else {
			row.Bounds, row.Ends, row.Left = b.Bounds, b.Ends, b.Ends.Sub(now).Round(time.Second).String()
		}
		out = append(out, row)
	}
	return out, nil
}