package reporting

import (
	"bytes"
	"compress/zlib"
	"io"
	"regexp"
	"strings"
	"testing"
	"time"

	"github.com/go-pdf/fpdf"
)

// TestExecutiveSummary_EmptyDataShowsNoData asserts that when a report
// runs against a window that produced zero data points and no alerts,
// the executive summary renders a muted "NO DATA" card rather than the
// green HEALTHY card it shipped with originally. This was a real UX
// bug found by generating an actual PDF: a user looking at an
// empty-window report would see "All systems operating normally" and
// believe their resource was fine when really Pulse had no metrics to
// evaluate.
func TestExecutiveSummary_EmptyDataShowsNoData(t *testing.T) {
	data := &ReportData{
		Title:        "Empty",
		ResourceType: "node",
		ResourceID:   "empty",
		Start:        time.Now().Add(-time.Hour),
		End:          time.Now(),
		GeneratedAt:  time.Now(),
		Metrics:      map[string][]MetricDataPoint{},
		Summary:      MetricSummary{ByMetric: map[string]MetricStats{}},
		TotalPoints:  0,
	}
	text := renderExecutiveSummaryText(t, data)
	if !strings.Contains(text, "NO DATA") {
		t.Errorf("expected 'NO DATA' card on empty data, got:\n%s", text)
	}
	if strings.Contains(text, "All systems operating normally") {
		t.Errorf("HEALTHY message should not appear on empty data, got:\n%s", text)
	}
}

// TestExecutiveSummary_HealthyWhenDataPresent_NoAlerts confirms the
// HEALTHY path still works when there IS data and no alerts. This is
// the regression guard: the empty-data fix above must not change the
// behavior for actually-quiet resources.
func TestExecutiveSummary_HealthyWhenDataPresent_NoAlerts(t *testing.T) {
	data := &ReportData{
		Title:        "Quiet",
		ResourceType: "node",
		ResourceID:   "quiet",
		Start:        time.Now().Add(-time.Hour),
		End:          time.Now(),
		GeneratedAt:  time.Now(),
		Summary: MetricSummary{ByMetric: map[string]MetricStats{
			"cpu":    {Avg: 5, Max: 12, Count: 60},
			"memory": {Avg: 30, Max: 35, Count: 60},
		}},
		TotalPoints: 120,
	}
	text := renderExecutiveSummaryText(t, data)
	if !strings.Contains(text, "HEALTHY") {
		t.Errorf("expected HEALTHY card on quiet resource, got:\n%s", text)
	}
}

// TestExecutiveSummary_HeuristicSourceShowsDiscoverabilityTip asserts
// that when the narrative came from the heuristic narrator (no AI
// configured or AI failed), the executive summary surfaces a one-line
// tip pointing operators at Pulse Assistant. Without this nudge a
// user has no signal that AI-narrated reports are a separate
// capability they could enable.
func TestExecutiveSummary_HeuristicSourceShowsDiscoverabilityTip(t *testing.T) {
	data := &ReportData{
		Title:        "Quiet",
		ResourceType: "node",
		ResourceID:   "quiet",
		Start:        time.Now().Add(-time.Hour),
		End:          time.Now(),
		GeneratedAt:  time.Now(),
		Summary: MetricSummary{ByMetric: map[string]MetricStats{
			"cpu": {Avg: 10, Max: 20, Count: 60},
		}},
		TotalPoints: 60,
		Narrative: &Narrative{
			Source:        NarrativeSourceHeuristic,
			HealthStatus:  "HEALTHY",
			HealthMessage: "OK",
			Observations:  []NarrativeBullet{{Text: "Looks fine", Severity: NarrativeSeverityOK}},
		},
	}
	text := renderExecutiveSummaryText(t, data)
	if !strings.Contains(text, "Configure Pulse Assistant") {
		t.Errorf("expected discoverability tip on heuristic-source narrative, got:\n%s", text)
	}
}

// TestExecutiveSummary_AISourceDoesNotShowDiscoverabilityTip is the
// converse: when AI actually fired, the disclaimer footer (which the
// AI narrator populates) replaces the tip. Showing both would be
// noisy and contradict the AI provenance line.
func TestExecutiveSummary_AISourceDoesNotShowDiscoverabilityTip(t *testing.T) {
	data := &ReportData{
		Title:        "Quiet",
		ResourceType: "node",
		ResourceID:   "quiet",
		Start:        time.Now().Add(-time.Hour),
		End:          time.Now(),
		GeneratedAt:  time.Now(),
		Summary: MetricSummary{ByMetric: map[string]MetricStats{
			"cpu": {Avg: 10, Max: 20, Count: 60},
		}},
		TotalPoints: 60,
		Narrative: &Narrative{
			Source:        NarrativeSourceAI,
			HealthStatus:  "HEALTHY",
			HealthMessage: "OK",
			Observations:  []NarrativeBullet{{Text: "AI prose here", Severity: NarrativeSeverityOK}},
			Disclaimer:    "Narrative generated by Pulse Assistant.",
		},
	}
	text := renderExecutiveSummaryText(t, data)
	if strings.Contains(text, "Configure Pulse Assistant") {
		t.Errorf("discoverability tip should not appear when AI fired, got:\n%s", text)
	}
	if !strings.Contains(text, "Narrative generated by Pulse Assistant") {
		t.Errorf("expected AI provenance disclaimer when source is ai, got:\n%s", text)
	}
}

// TestFleetSummary_HeuristicSourceShowsDiscoverabilityTip mirrors the
// single-resource test for the fleet path. The fleet narrative has a
// distinct nudge (mentions outliers / patterns) so the copy doesn't
// over-promise single-resource synthesis.
func TestFleetSummary_HeuristicSourceShowsDiscoverabilityTip(t *testing.T) {
	now := time.Now()
	multi := &MultiReportData{
		Title:       "Fleet",
		Start:       now.Add(-time.Hour),
		End:         now,
		GeneratedAt: now,
		Resources: []*ReportData{
			{
				ResourceID:   "a",
				ResourceType: "node",
				Resource:     &ResourceInfo{Name: "alpha", Status: "online"},
				Summary:      MetricSummary{ByMetric: map[string]MetricStats{"cpu": {Avg: 10, Max: 15, Count: 60}}},
				TotalPoints:  60,
			},
		},
		FleetNarrative: &FleetNarrative{
			Source:        NarrativeSourceHeuristic,
			HealthStatus:  "HEALTHY",
			HealthMessage: "Fleet quiet",
		},
	}
	text := renderFleetSummaryText(t, multi)
	if !strings.Contains(text, "Configure Pulse Assistant") {
		t.Errorf("expected fleet discoverability tip on heuristic source, got:\n%s", text)
	}
	if !strings.Contains(text, "outliers") && !strings.Contains(text, "patterns") {
		t.Errorf("fleet tip should mention outliers/patterns, got:\n%s", text)
	}
}

// renderExecutiveSummaryText runs writeExecutiveSummary against a
// fresh fpdf, extracts text by parsing the resulting PDF, and returns
// the rendered text content. Used by the UX assertions above.
func renderExecutiveSummaryText(t *testing.T, data *ReportData) string {
	t.Helper()
	gen := NewPDFGenerator()
	bytes, err := gen.Generate(data)
	if err != nil {
		t.Fatalf("Generate: %v", err)
	}
	return extractPDFText(t, bytes)
}

func renderFleetSummaryText(t *testing.T, data *MultiReportData) string {
	t.Helper()
	gen := NewPDFGenerator()
	bytes, err := gen.GenerateMulti(data)
	if err != nil {
		t.Fatalf("GenerateMulti: %v", err)
	}
	return extractPDFText(t, bytes)
}

// extractPDFText pulls plain text out of a PDF blob by finding every
// FlateDecode'd content stream, inflating it, and harvesting the
// parenthesised string literals used by Tj operators. fpdf always
// compresses its content streams, so a substring scan over the raw
// bytes misses everything visible to a reader.
var streamRe = regexp.MustCompile(`(?s)stream\r?\n(.*?)\r?\nendstream`)
var literalRe = regexp.MustCompile(`\(([^()\\]*(?:\\.[^()\\]*)*)\)`)

func extractPDFText(t *testing.T, data []byte) string {
	t.Helper()
	var out bytes.Buffer
	for _, m := range streamRe.FindAllSubmatch(data, -1) {
		raw := m[1]
		decoded, err := inflateStream(raw)
		if err != nil {
			// Stream may not be Flate'd (e.g. xref tables) — skip.
			continue
		}
		for _, lit := range literalRe.FindAllSubmatch(decoded, -1) {
			out.Write(lit[1])
			out.WriteByte(' ')
		}
	}
	return out.String()
}

func inflateStream(b []byte) ([]byte, error) {
	r, err := zlib.NewReader(bytes.NewReader(b))
	if err != nil {
		return nil, err
	}
	defer r.Close()
	return io.ReadAll(r)
}

// Compile-time assertion the fpdf import isn't dropped by goimports
// when this test file is processed in isolation; the import lives in
// pdf.go but tests referencing fpdf.New constants confirm we still
// resolve the package.
var _ = fpdf.New