package platform

import (
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"time"
)

func renderBenchmarkReport(result NvidiaBenchmarkResult) string {
	return renderBenchmarkReportWithCharts(result, nil)
}

type benchmarkReportChart struct {
	Title   string
	Content string
}

var ansiEscapePattern = regexp.MustCompile(`\x1b\[[0-9;]*m`)

func renderBenchmarkReportWithCharts(result NvidiaBenchmarkResult, charts []benchmarkReportChart) string {
	var b strings.Builder

	// ── Header ────────────────────────────────────────────────────────────────
	b.WriteString("# Bee NVIDIA Benchmark Report\n\n")

	// System identity block
	if result.ServerModel != "" {
		fmt.Fprintf(&b, "**Server:** %s  \n", result.ServerModel)
	}
	if result.Hostname != "" {
		fmt.Fprintf(&b, "**Host:** %s  \n", result.Hostname)
	}
	// GPU models summary
	if len(result.GPUs) > 0 {
		modelCount := make(map[string]int)
		var modelOrder []string
		for _, g := range result.GPUs {
			m := strings.TrimSpace(g.Name)
			if m == "" {
				m = "Unknown GPU"
			}
			if modelCount[m] == 0 {
				modelOrder = append(modelOrder, m)
			}
			modelCount[m]++
		}
		var parts []string
		for _, m := range modelOrder {
			if modelCount[m] == 1 {
				parts = append(parts, m)
			} else {
				parts = append(parts, fmt.Sprintf("%d× %s", modelCount[m], m))
			}
		}
		fmt.Fprintf(&b, "**GPU(s):** %s  \n", strings.Join(parts, ", "))
	}
	fmt.Fprintf(&b, "**Profile:** %s  \n", result.BenchmarkProfile)
	fmt.Fprintf(&b, "**App version:** %s  \n", result.BenchmarkVersion)
	fmt.Fprintf(&b, "**Generated:** %s  \n", result.GeneratedAt.Format("2006-01-02 15:04:05 UTC"))
	if result.ParallelGPUs {
		fmt.Fprintf(&b, "**Mode:** parallel (all GPUs simultaneously)  \n")
	}
	fmt.Fprintf(&b, "**Overall status:** %s  \n", result.OverallStatus)
	b.WriteString("\n")

	// ── Executive Summary ─────────────────────────────────────────────────────
	if len(result.Findings) > 0 {
		b.WriteString("## Executive Summary\n\n")
		for _, finding := range result.Findings {
			fmt.Fprintf(&b, "- %s\n", finding)
		}
		b.WriteString("\n")
	}

	if len(result.Warnings) > 0 {
		b.WriteString("## Warnings\n\n")
		for _, warning := range result.Warnings {
			fmt.Fprintf(&b, "- %s\n", warning)
		}
		b.WriteString("\n")
	}

	// ── Scorecard table ───────────────────────────────────────────────────────
	b.WriteString("## Scorecard\n\n")
	b.WriteString("| GPU | Status | Composite | Compute | TOPS/SM/GHz | Power Sustain | Thermal Sustain | Stability | Interconnect |\n")
	b.WriteString("|-----|--------|-----------|---------|-------------|---------------|-----------------|-----------|-------------|\n")
	for _, gpu := range result.GPUs {
		name := strings.TrimSpace(gpu.Name)
		if name == "" {
			name = "Unknown"
		}
		interconnect := "-"
		if gpu.Scores.InterconnectScore > 0 {
			interconnect = fmt.Sprintf("%.1f", gpu.Scores.InterconnectScore)
		}
		topsPerSM := "-"
		if gpu.Scores.TOPSPerSMPerGHz > 0 {
			topsPerSM = fmt.Sprintf("%.3f", gpu.Scores.TOPSPerSMPerGHz)
		}
		fmt.Fprintf(&b, "| GPU %d %s | %s | **%.2f** | %.2f | %s | %.1f | %.1f | %.1f | %s |\n",
			gpu.Index, name,
			gpu.Status,
			gpu.Scores.CompositeScore,
			gpu.Scores.ComputeScore,
			topsPerSM,
			gpu.Scores.PowerSustainScore,
			gpu.Scores.ThermalSustainScore,
			gpu.Scores.StabilityScore,
			interconnect,
		)
	}
	b.WriteString("\n")

	// ── Per GPU detail ────────────────────────────────────────────────────────
	b.WriteString("## Per-GPU Details\n\n")
	for _, gpu := range result.GPUs {
		name := strings.TrimSpace(gpu.Name)
		if name == "" {
			name = "Unknown GPU"
		}
		fmt.Fprintf(&b, "### GPU %d — %s\n\n", gpu.Index, name)

		// Identity
		if gpu.BusID != "" {
			fmt.Fprintf(&b, "- **Bus ID:** %s\n", gpu.BusID)
		}
		if gpu.VBIOS != "" {
			fmt.Fprintf(&b, "- **vBIOS:** %s\n", gpu.VBIOS)
		}
		if gpu.ComputeCapability != "" {
			fmt.Fprintf(&b, "- **Compute capability:** %s\n", gpu.ComputeCapability)
		}
		if gpu.MultiprocessorCount > 0 {
			fmt.Fprintf(&b, "- **SMs:** %d\n", gpu.MultiprocessorCount)
		}
		if gpu.PowerLimitW > 0 {
			fmt.Fprintf(&b, "- **Power limit:** %.0f W (default %.0f W)\n", gpu.PowerLimitW, gpu.DefaultPowerLimitW)
		}
		if gpu.LockedGraphicsClockMHz > 0 {
			fmt.Fprintf(&b, "- **Locked clocks:** GPU %.0f MHz / Mem %.0f MHz\n", gpu.LockedGraphicsClockMHz, gpu.LockedMemoryClockMHz)
		}
		b.WriteString("\n")

		// Steady-state telemetry
		fmt.Fprintf(&b, "**Steady-state telemetry** (%ds):\n\n", int(gpu.Steady.DurationSec))
		b.WriteString("| | Avg | P95 |\n|---|---|---|\n")
		fmt.Fprintf(&b, "| Power | %.1f W | %.1f W |\n", gpu.Steady.AvgPowerW, gpu.Steady.P95PowerW)
		fmt.Fprintf(&b, "| Temperature | %.1f °C | %.1f °C |\n", gpu.Steady.AvgTempC, gpu.Steady.P95TempC)
		fmt.Fprintf(&b, "| GPU clock | %.0f MHz | %.0f MHz |\n", gpu.Steady.AvgGraphicsClockMHz, gpu.Steady.P95GraphicsClockMHz)
		fmt.Fprintf(&b, "| Memory clock | %.0f MHz | %.0f MHz |\n", gpu.Steady.AvgMemoryClockMHz, gpu.Steady.P95MemoryClockMHz)
		fmt.Fprintf(&b, "| GPU utilisation | %.1f %% | — |\n", gpu.Steady.AvgUsagePct)
		b.WriteString("\n")

		// Throttle
		throttle := formatThrottleLine(gpu.Throttle, gpu.Steady.DurationSec)
		if throttle != "none" {
			fmt.Fprintf(&b, "**Throttle:** %s\n\n", throttle)
		}

		// Precision results
		if len(gpu.PrecisionResults) > 0 {
			b.WriteString("**Precision results:**\n\n")
			b.WriteString("| Precision | TOPS | Lanes | Iterations |\n|-----------|------|-------|------------|\n")
			for _, p := range gpu.PrecisionResults {
				if p.Supported {
					fmt.Fprintf(&b, "| %s | %.2f | %d | %d |\n", p.Name, p.TeraOpsPerSec, p.Lanes, p.Iterations)
				} else {
					fmt.Fprintf(&b, "| %s | — (unsupported) | — | — |\n", p.Name)
				}
			}
			b.WriteString("\n")
		}

		// Degradation / Notes
		if len(gpu.DegradationReasons) > 0 {
			fmt.Fprintf(&b, "**Degradation reasons:** %s\n\n", strings.Join(gpu.DegradationReasons, ", "))
		}
		if len(gpu.Notes) > 0 {
			b.WriteString("**Notes:**\n\n")
			for _, note := range gpu.Notes {
				fmt.Fprintf(&b, "- %s\n", note)
			}
			b.WriteString("\n")
		}
	}

	// ── Interconnect ──────────────────────────────────────────────────────────
	if result.Interconnect != nil {
		b.WriteString("## Interconnect (NCCL)\n\n")
		fmt.Fprintf(&b, "**Status:** %s\n\n", result.Interconnect.Status)
		if result.Interconnect.Supported {
			b.WriteString("| Metric | Avg | Max |\n|--------|-----|-----|\n")
			fmt.Fprintf(&b, "| Alg BW | %.1f GB/s | %.1f GB/s |\n", result.Interconnect.AvgAlgBWGBps, result.Interconnect.MaxAlgBWGBps)
			fmt.Fprintf(&b, "| Bus BW | %.1f GB/s | %.1f GB/s |\n", result.Interconnect.AvgBusBWGBps, result.Interconnect.MaxBusBWGBps)
			b.WriteString("\n")
		}
		for _, note := range result.Interconnect.Notes {
			fmt.Fprintf(&b, "- %s\n", note)
		}
		if len(result.Interconnect.Notes) > 0 {
			b.WriteString("\n")
		}
	}

	// ── Server Power (IPMI) ───────────────────────────────────────────────────
	if sp := result.ServerPower; sp != nil {
		b.WriteString("## Server Power (IPMI)\n\n")
		if !sp.Available {
			b.WriteString("IPMI power measurement unavailable.\n\n")
		} else {
			b.WriteString("| | Value |\n|---|---|\n")
			fmt.Fprintf(&b, "| Server idle | %.0f W |\n", sp.IdleW)
			fmt.Fprintf(&b, "| Server under load | %.0f W |\n", sp.LoadedW)
			fmt.Fprintf(&b, "| Server delta (load − idle) | %.0f W |\n", sp.DeltaW)
			fmt.Fprintf(&b, "| GPU-reported sum | %.0f W |\n", sp.GPUReportedSumW)
			if sp.ReportingRatio > 0 {
				fmt.Fprintf(&b, "| Reporting ratio | %.2f (1.0 = accurate, <0.75 = GPU over-reports) |\n", sp.ReportingRatio)
			}
			b.WriteString("\n")
		}
		for _, note := range sp.Notes {
			fmt.Fprintf(&b, "- %s\n", note)
		}
		if len(sp.Notes) > 0 {
			b.WriteString("\n")
		}
	}

	// ── Terminal charts (steady-state only) ───────────────────────────────────
	if len(charts) > 0 {
		b.WriteString("## Steady-State Charts\n\n")
		for _, chart := range charts {
			content := strings.TrimSpace(stripANSIEscapeSequences(chart.Content))
			if content == "" {
				continue
			}
			fmt.Fprintf(&b, "### %s\n\n```\n%s\n```\n\n", chart.Title, content)
		}
	}

	// ── Methodology ───────────────────────────────────────────────────────────
	b.WriteString("## Methodology\n\n")
	fmt.Fprintf(&b, "- Profile `%s` uses standardized baseline → warmup → steady-state → interconnect → cooldown phases.\n", result.BenchmarkProfile)
	b.WriteString("- Single-GPU compute score from bee-gpu-burn cuBLASLt when available.\n")
	b.WriteString("- Thermal and power limitations inferred from NVIDIA clock event reason counters and sustained telemetry.\n")
	b.WriteString("- `result.json` is the canonical machine-readable source for this benchmark run.\n\n")

	// ── Raw files ─────────────────────────────────────────────────────────────
	b.WriteString("## Raw Files\n\n")
	b.WriteString("- `result.json`\n- `report.md`\n- `summary.txt`\n- `verbose.log`\n")
	b.WriteString("- `gpu-*-baseline-metrics.csv/html/term.txt`\n")
	b.WriteString("- `gpu-*-warmup.log`\n")
	b.WriteString("- `gpu-*-steady.log`\n")
	b.WriteString("- `gpu-*-steady-metrics.csv/html/term.txt`\n")
	b.WriteString("- `gpu-*-cooldown-metrics.csv/html/term.txt`\n")
	if result.Interconnect != nil {
		b.WriteString("- `nccl-all-reduce.log`\n")
	}
	return b.String()
}

// loadBenchmarkReportCharts loads only steady-state terminal charts (baseline and
// cooldown charts are not useful for human review).
func loadBenchmarkReportCharts(runDir string, gpuIndices []int) []benchmarkReportChart {
	var charts []benchmarkReportChart
	for _, idx := range gpuIndices {
		path := filepath.Join(runDir, fmt.Sprintf("gpu-%d-steady-metrics-term.txt", idx))
		raw, err := os.ReadFile(path)
		if err != nil || len(raw) == 0 {
			continue
		}
		charts = append(charts, benchmarkReportChart{
			Title:   fmt.Sprintf("GPU %d — Steady State", idx),
			Content: string(raw),
		})
	}
	return charts
}

func stripANSIEscapeSequences(raw string) string {
	return ansiEscapePattern.ReplaceAllString(raw, "")
}

// formatThrottleLine renders throttle counters as human-readable percentages of
// the steady-state window.  Only non-zero counters are shown.  When the steady
// duration is unknown (0), raw seconds are shown instead.
func formatThrottleLine(t BenchmarkThrottleCounters, steadyDurationSec float64) string {
	type counter struct {
		label string
		us    uint64
	}
	counters := []counter{
		{"sw_power", t.SWPowerCapUS},
		{"sw_thermal", t.SWThermalSlowdownUS},
		{"sync_boost", t.SyncBoostUS},
		{"hw_thermal", t.HWThermalSlowdownUS},
		{"hw_power_brake", t.HWPowerBrakeSlowdownUS},
	}
	var parts []string
	for _, c := range counters {
		if c.us == 0 {
			continue
		}
		sec := float64(c.us) / 1e6
		if steadyDurationSec > 0 {
			pct := sec / steadyDurationSec * 100
			parts = append(parts, fmt.Sprintf("%s=%.1f%% (%.0fs)", c.label, pct, sec))
		} else if sec < 1 {
			parts = append(parts, fmt.Sprintf("%s=%.0fms", c.label, sec*1000))
		} else {
			parts = append(parts, fmt.Sprintf("%s=%.1fs", c.label, sec))
		}
	}
	if len(parts) == 0 {
		return "none"
	}
	return strings.Join(parts, "  ")
}

func renderBenchmarkSummary(result NvidiaBenchmarkResult) string {
	var b strings.Builder
	fmt.Fprintf(&b, "run_at_utc=%s\n", result.GeneratedAt.Format(time.RFC3339))
	fmt.Fprintf(&b, "benchmark_profile=%s\n", result.BenchmarkProfile)
	fmt.Fprintf(&b, "overall_status=%s\n", result.OverallStatus)
	fmt.Fprintf(&b, "gpu_count=%d\n", len(result.GPUs))
	fmt.Fprintf(&b, "normalization_status=%s\n", result.Normalization.Status)
	var best float64
	for i, gpu := range result.GPUs {
		fmt.Fprintf(&b, "gpu_%d_status=%s\n", gpu.Index, gpu.Status)
		fmt.Fprintf(&b, "gpu_%d_composite_score=%.2f\n", gpu.Index, gpu.Scores.CompositeScore)
		if i == 0 || gpu.Scores.CompositeScore > best {
			best = gpu.Scores.CompositeScore
		}
	}
	fmt.Fprintf(&b, "best_composite_score=%.2f\n", best)
	if result.Interconnect != nil {
		fmt.Fprintf(&b, "interconnect_status=%s\n", result.Interconnect.Status)
		fmt.Fprintf(&b, "interconnect_max_busbw_gbps=%.1f\n", result.Interconnect.MaxBusBWGBps)
	}
	return b.String()
}