package web

import (
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/m/projax/internal/aggregate"
	"github.com/m/projax/store"
)

// dashboardActivityWindow is the lookback IsCurrent uses to decide whether
// a project sits on the primary Tiles grid or under the Quiet (N) ▾ fold.
// 14 days per the Phase 5h §7 contract — long enough to catch a project
// that shipped last week but is between sprints, short enough that a
// project nobody's touched in three weeks doesn't crowd the top.
const dashboardActivityWindow = 14 * 24 * time.Hour

// dashboardProject is the per-project rollup that drives the Tiles view.
// One row per item.ID across every signal source (CalDAV, Gitea, dated
// links). Built from the same aggregator outputs the existing cards
// already fetch — no extra DAV/Gitea calls.
type dashboardProject struct {
	Item            *store.Item
	OpenTasks       int       // open VTODOs across every linked calendar
	Overdue         int       // subset of OpenTasks with Due strictly before today
	OpenIssues      int       // open Gitea issues across every linked repo
	LastActivity    time.Time // zero = no signal seen yet
	LastActivityRel string    // "2d" / "3h" / "12m" / "now"; "" when zero
	NextSignal      string    // soonest-due open VTODO summary, else latest issue title, else ""
	NextSignalKind  string    // "task" | "issue" | ""
	IsLive          bool      // has public_live_url
	Stale           bool      // mai-managed quiet-repo + 0 open work — fed by the existing stale set
}

// IsCurrent implements the §7 rule: pinned OR open-tasks > 0 OR
// open-issues > 0 OR LastActivity within dashboardActivityWindow.
func (p dashboardProject) IsCurrent(now time.Time) bool {
	if p.Item != nil && p.Item.Pinned {
		return true
	}
	if p.OpenTasks > 0 || p.OpenIssues > 0 {
		return true
	}
	if !p.LastActivity.IsZero() && now.Sub(p.LastActivity) < dashboardActivityWindow {
		return true
	}
	return false
}

// collectProjectRollups groups the aggregator's per-row signals by
// item.ID into one dashboardProject per item, then sorts the output
// pinned-first then by primary path ascending. Rollups are returned for
// every item even when every signal is zero — the caller (IsCurrent +
// the Tiles template) decides what surfaces.
//
// repoActivity is optional: when set, item.ID → newest repo updated_at
// feeds the LastActivity max. The existing stale collector already
// fetches repo updated_at, so the dashboard wiring (Slice 2) can pass
// it through without a second Gitea round-trip.
//
// staleByItem is optional: when set, item.ID → true tags the rollup
// with the Stale flag so the Quiet fold can badge it without re-running
// the staleness probe.
func collectProjectRollups(
	items []*store.Item,
	todos []aggregate.TodoRow,
	issues []aggregate.IssueRow,
	events []aggregate.EventRow,
	docs []*store.ItemLinkWithItem,
	repoActivity map[string]time.Time,
	staleByItem map[string]bool,
	now time.Time,
) []dashboardProject {
	today := startOfDay(now)
	byID := make(map[string]*dashboardProject, len(items))
	for _, it := range items {
		byID[it.ID] = &dashboardProject{
			Item:   it,
			IsLive: strings.TrimSpace(it.PublicLiveURL) != "",
			Stale:  staleByItem[it.ID],
		}
	}

	// Soonest-due open VTODO per item wins NextSignal (task kind).
	// Done/cancelled VTODOs still contribute LastActivity via LastModified
	// so a project that shipped tasks recently surfaces as current.
	soonestDue := map[string]time.Time{}
	for i := range todos {
		td := &todos[i]
		p, ok := byID[td.Item.ID]
		if !ok {
			continue
		}
		status := td.Todo.Status
		if status == "COMPLETED" || status == "CANCELLED" {
			if td.Todo.LastModified != nil && td.Todo.LastModified.After(p.LastActivity) {
				p.LastActivity = *td.Todo.LastModified
			}
			continue
		}
		p.OpenTasks++
		if td.Todo.Due != nil {
			if startOfDay(td.Todo.Due.Local()).Before(today) {
				p.Overdue++
			}
			cur, seen := soonestDue[td.Item.ID]
			if !seen || td.Todo.Due.Before(cur) {
				soonestDue[td.Item.ID] = *td.Todo.Due
				p.NextSignal = td.Todo.Summary
				p.NextSignalKind = "task"
			}
		} else if p.NextSignal == "" {
			// No-due task: only fills NextSignal if nothing else has yet.
			p.NextSignal = td.Todo.Summary
			p.NextSignalKind = "task"
		}
		if td.Todo.LastModified != nil && td.Todo.LastModified.After(p.LastActivity) {
			p.LastActivity = *td.Todo.LastModified
		}
	}

	// Issues feed OpenIssues + LastActivity. NextSignal only when no task
	// has claimed the slot yet — tasks are more actionable per m's daily
	// driver pattern.
	latestIssueUpd := map[string]time.Time{}
	for i := range issues {
		ir := &issues[i]
		p, ok := byID[ir.Item.ID]
		if !ok {
			continue
		}
		p.OpenIssues++
		prev := latestIssueUpd[ir.Item.ID]
		if ir.Issue.UpdatedAt.After(prev) {
			latestIssueUpd[ir.Item.ID] = ir.Issue.UpdatedAt
			if p.NextSignalKind != "task" {
				p.NextSignal = ir.Issue.Title
				p.NextSignalKind = "issue"
			}
		}
		if ir.Issue.UpdatedAt.After(p.LastActivity) {
			p.LastActivity = ir.Issue.UpdatedAt
		}
	}

	// Events feed LastActivity only — they don't appear on tiles but a
	// recent or imminent event keeps the project current via the window.
	for i := range events {
		ev := &events[i]
		p, ok := byID[ev.Item.ID]
		if !ok {
			continue
		}
		if ev.Event.Start.After(p.LastActivity) {
			p.LastActivity = ev.Event.Start
		}
	}

	// Dated links feed LastActivity via event_date.
	for _, d := range docs {
		if d == nil || d.Link.EventDate == nil {
			continue
		}
		p, ok := byID[d.Link.ItemID]
		if !ok {
			continue
		}
		if d.Link.EventDate.After(p.LastActivity) {
			p.LastActivity = *d.Link.EventDate
		}
	}

	// Repo activity from the stale-card probe (optional, no extra fetch).
	for itemID, at := range repoActivity {
		p, ok := byID[itemID]
		if !ok || at.IsZero() {
			continue
		}
		if at.After(p.LastActivity) {
			p.LastActivity = at
		}
	}

	out := make([]dashboardProject, 0, len(byID))
	for _, p := range byID {
		if !p.LastActivity.IsZero() {
			p.LastActivityRel = activityRel(now, p.LastActivity)
		}
		out = append(out, *p)
	}
	sort.SliceStable(out, func(i, j int) bool {
		ai, aj := out[i].Item.Pinned, out[j].Item.Pinned
		if ai != aj {
			return ai
		}
		return out[i].Item.PrimaryPath() < out[j].Item.PrimaryPath()
	})
	return out
}

// activityRel formats a tight relative-time label for the tile stamp.
// Different shape from relativeTime (used on rows) — tiles have less
// horizontal space, one-or-two-character labels read better.
//
//	<1m   → "now"
//	<1h   → "12m"
//	<24h  → "3h"
//	else  → "5d"
//
// Future timestamps (e.g. an event tomorrow) are flipped to absolute
// duration so the label still reads sensibly — "in 14h" would push the
// column wider than the design allows.
func activityRel(now, t time.Time) string {
	d := now.Sub(t)
	if d < 0 {
		d = -d
	}
	switch {
	case d < time.Minute:
		return "now"
	case d < time.Hour:
		return strconv.Itoa(int(d/time.Minute)) + "m"
	case d < 24*time.Hour:
		return strconv.Itoa(int(d/time.Hour)) + "h"
	default:
		return strconv.Itoa(int(d/(24*time.Hour))) + "d"
	}
}