package webui

import (
	"encoding/json"
	"fmt"
	"html"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"

	"bee/audit/internal/platform"
	"bee/audit/internal/schema"
)

// renderTopo renders the /topo page: a read-only visualization of the server
// topology (CPU sockets, NUMA-affine PCIe devices, PSU/BMC) plus a separate
// NVLink topology card. It is pure visualization: everything it reads either
// already exists in the audit.json contract, or comes from the persisted
// techdump captured once per audit cycle (platform.CaptureTechnicalDump) —
// nothing here shells out to nvidia-smi itself, writes to
// schema.HardwarePCIeDevice or any other contract type, or talks to
// Reanimator Core.
func renderTopo(opts HandlerOptions) string {
	data, err := loadSnapshot(opts.AuditPath)
	if err != nil {
		return topoCard("Topology", `<span class="badge badge-unknown">No audit data</span>`)
	}
	var ingest schema.HardwareIngestRequest
	if err := json.Unmarshal(data, &ingest); err != nil {
		return topoCard("Topology", `<span class="badge badge-err">Parse error</span>`)
	}
	hw := ingest.Hardware

	var b strings.Builder
	b.WriteString(renderTopoMainDiagram(hw, opts.ExportDir))
	if nv := renderTopoNVLinkCard(hw, opts.ExportDir); nv != "" {
		b.WriteString(nv)
	}
	return b.String()
}

func topoCard(title, body string) string {
	return `<div class="card"><div class="card-head">` + html.EscapeString(title) + `</div><div class="card-body">` + body + `</div></div>`
}

// ---------------------------------------------------------------------------
// Classification helpers
//
// webui does not import collector (matches the existing isGPUDeviceClass
// precedent in pages.go, which already locally duplicates collector.isGPUClass
// instead of importing the package for one classifier).
// ---------------------------------------------------------------------------

// isNICDeviceClassDev applies isNICDeviceClass (pages.go) to a single device,
// with a MAC-address fallback for devices lspci doesn't classify as NIC.
func isNICDeviceClassDev(dev schema.HardwarePCIeDevice) bool {
	if dev.DeviceClass != nil && isNICDeviceClass(*dev.DeviceClass) {
		return true
	}
	return len(dev.MacAddresses) > 0
}

// isRAIDControllerClass matches the canonical class strings produced by
// collector.mapPCIeDeviceClass for RAID/storage HBAs.
func isRAIDControllerClass(class string) bool {
	switch strings.TrimSpace(class) {
	case "MassStorageController", "StorageController":
		return true
	default:
		return false
	}
}

// ---------------------------------------------------------------------------
// Status / link-speed coloring
// ---------------------------------------------------------------------------

// pcieGenRank ranks a PCIe generation label ("Gen3", "Gen4", ...) for
// comparison. Mirrors collector.pcieLinkSpeedRank's ordering; duplicated
// locally rather than exported, per the same "no collector import in webui"
// convention used for isGPUDeviceClass/isRAIDControllerClass.
func pcieGenRank(gen string) int {
	gen = strings.ToLower(strings.TrimSpace(gen))
	gen = strings.TrimPrefix(gen, "gen")
	n, err := strconv.Atoi(gen)
	if err != nil {
		return 0
	}
	return n
}

// topoEdgeColorVar computes the CPU->device edge color strictly from
// link_speed vs max_link_speed — NOT from dev.Status, since Status can also
// be overwritten by SAT/acceptance-test results on the same PCIe device,
// which would conflate "link is physically degraded" with "this GPU failed
// its stress test" into the same color.
func topoEdgeColorVar(dev schema.HardwarePCIeDevice) string {
	if dev.LinkSpeed == nil || dev.MaxLinkSpeed == nil {
		return "var(--muted)"
	}
	if pcieGenRank(*dev.LinkSpeed) < pcieGenRank(*dev.MaxLinkSpeed) {
		return "var(--warn-fg)"
	}
	return "var(--ok-fg)"
}

// ---------------------------------------------------------------------------
// NUMA node -> CPU socket join (heuristic, no guaranteed hardware mapping)
// ---------------------------------------------------------------------------

// buildSocketIndex maps a NUMA node number to the index into cpus for the
// socket occupying that position in ascending Socket-designation order.
//
// Linux NUMA node numbering is always 0-based (node0, node1, ...), but
// dmidecode's "Socket Designation" is board-defined and frequently 1-based
// ("CPU1", "CPU2", ...). Mapping NUMA node N to the CPU whose Socket field
// equals N (as an earlier version of this function did) silently fails on
// any 1-indexed board: node 0 has no match (dropped into the "unknown"
// column) and node 1 wrongly maps to the first CPU. Ranking by Socket value
// instead assumes only that node order follows socket order — true for the
// common case of N-socket boards — without depending on the numbering base.
func buildSocketIndex(cpus []schema.HardwareCPU) map[int]int {
	order := make([]int, len(cpus))
	for i := range cpus {
		order[i] = i
	}
	sort.SliceStable(order, func(a, b int) bool {
		ca, cb := cpus[order[a]], cpus[order[b]]
		sa, sb := 0, 0
		if ca.Socket != nil {
			sa = *ca.Socket
		}
		if cb.Socket != nil {
			sb = *cb.Socket
		}
		return sa < sb
	})
	idx := map[int]int{}
	for numaNode, cpuIdx := range order {
		idx[numaNode] = cpuIdx
	}
	return idx
}

// ---------------------------------------------------------------------------
// DIMM -> CPU column attachment
//
// schema.HardwareMemory has no NUMANode field (unlike HardwarePCIeDevice), so
// unlike the GPU/NIC/RAID placement above, a DIMM's CPU affinity has to be
// read out of its own Locator/Bank Locator strings — DMI type 17 gives no
// other hint. Both patterns below have been observed on real boards.
// ---------------------------------------------------------------------------

var (
	topoMemCPULocatorRe = regexp.MustCompile(`(?i)^cpu\s*0*(\d+)`)
	topoMemBankNodeRe   = regexp.MustCompile(`(?i)node\s*0*(\d+)`)
)

// parseDIMMBankLocatorNodes maps a DIMM's Locator (matches
// schema.HardwareMemory.Slot) to the node number embedded in its Bank
// Locator field (e.g. "_Node1_Channel0_Dimm0"), read from a raw
// "dmidecode -t 17" techdump capture. Bank Locator never reaches audit.json
// (schema.HardwareMemory.Location is json:"-", used only for internal DIMM
// telemetry matching), so boards whose Locator has no CPU number of its own
// (e.g. "DIMM000(A)" rather than "CPU0_DIMM_A1") need this fallback to
// attach a DIMM to a CPU column at all — matches the existing convention of
// reading extra techdump for this page's visualization only (see
// readTopoTechDump).
func parseDIMMBankLocatorNodes(raw string) map[string]int {
	result := map[string]int{}
	for _, sec := range strings.Split(raw, "Memory Device") {
		var locator string
		node := -1
		for _, line := range strings.Split(sec, "\n") {
			trimmed := strings.TrimSpace(line)
			if v, ok := strings.CutPrefix(trimmed, "Locator:"); ok {
				locator = strings.TrimSpace(v)
			}
			if v, ok := strings.CutPrefix(trimmed, "Bank Locator:"); ok {
				if m := topoMemBankNodeRe.FindStringSubmatch(v); m != nil {
					if n, err := strconv.Atoi(m[1]); err == nil {
						node = n
					}
				}
			}
		}
		if locator != "" && node >= 0 {
			result[locator] = node
		}
	}
	return result
}

// dimmRawNode returns the raw (vendor-numbered, not yet column-mapped)
// CPU/NUMA node number for a DIMM, trying two heuristics in order:
//  1. A CPU number encoded directly in the Locator itself, e.g.
//     "CPU0_DIMM_A1".
//  2. A node number from the Bank Locator via parseDIMMBankLocatorNodes,
//     e.g. Locator "DIMM000(A)" whose Bank Locator is
//     "_Node1_Channel0_Dimm0" -> 1.
//
// ok=false means neither pattern matched, so this DIMM can't be confidently
// attached to a CPU column and falls back to the unattached Memory row.
func dimmRawNode(mem schema.HardwareMemory, bankNodeByLocator map[string]int) (int, bool) {
	if mem.Slot == nil {
		return 0, false
	}
	if m := topoMemCPULocatorRe.FindStringSubmatch(*mem.Slot); m != nil {
		if n, err := strconv.Atoi(m[1]); err == nil {
			return n, true
		}
	}
	if n, ok := bankNodeByLocator[*mem.Slot]; ok {
		return n, true
	}
	return 0, false
}

// buildMemoryColumnIndex ranks the distinct raw node numbers seen across all
// DIMMs and maps the i-th smallest to column i — the same "node order
// follows socket order" assumption buildSocketIndex makes for PCIe NUMA
// nodes, but computed independently from PCIe's own numbering: PCIe's
// NUMANode is 0-based Linux numbering, while a DIMM's Bank Locator "NodeN"
// has been observed 1-based on at least one real board, so the two node
// spaces are not guaranteed to share a base.
func buildMemoryColumnIndex(rawNodes []int) map[int]int {
	seen := map[int]bool{}
	var distinct []int
	for _, n := range rawNodes {
		if !seen[n] {
			seen[n] = true
			distinct = append(distinct, n)
		}
	}
	sort.Ints(distinct)
	idx := map[int]int{}
	for col, n := range distinct {
		idx[n] = col
	}
	return idx
}

// ---------------------------------------------------------------------------
// GPU pairwise NVLink adjacency (from a live "nvidia-smi topo -m" query)
// ---------------------------------------------------------------------------

type gpuPairLink = platform.NvidiaNVLinkBondedPair

// parseGPUPairAdjacency returns every GPU pair with a nonzero NVLink bond
// count from a "nvidia-smi topo -m" matrix. Unlike parseNVIDIATopologyMatrix
// (collector package, aggregate-only: min/all-active/count), this returns
// who is bonded to whom — required so GPU-GPU edges are drawn for actually
// bonded pairs, not for adjacent boxes in the layout.
func parseGPUPairAdjacency(raw string) []gpuPairLink {
	return platform.ParseNvidiaNVLinkBondedPairs(raw)
}

// readTopoTechDump reads a file previously captured into the persistent
// techdump directory by platform.System.CaptureTechnicalDump (run once per
// audit cycle), rather than shelling out to nvidia-smi from the HTTP request
// handler — a live call here would block page rendering on a wedged driver,
// exactly the failure mode this tool exists to diagnose.
func readTopoTechDump(exportDir, name string) (string, error) {
	out, err := os.ReadFile(filepath.Join(exportDir, "techdump", name))
	if err != nil {
		return "", err
	}
	return string(out), nil
}

func readGPUTopologyMatrix(exportDir string) (string, error) {
	return readTopoTechDump(exportDir, "nvidia-smi-topo.txt")
}

// readNVIDIAIndexByBDF parses the persisted nvidia-smi-query.csv techdump
// (index,pci.bus_id,...) to map PCI bus address (matching
// HardwarePCIeDevice.Slot) to the GPU index nvidia-smi/topo -m reports, so
// GPU-GPU edges (keyed by index) can be anchored to the correct box (keyed
// by BDF) in the diagram.
func readNVIDIAIndexByBDF(exportDir string) (map[string]int, error) {
	raw, err := readTopoTechDump(exportDir, "nvidia-smi-query.csv")
	if err != nil {
		return nil, err
	}
	result := map[string]int{}
	for _, line := range strings.Split(raw, "\n") {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		parts := strings.Split(line, ",")
		if len(parts) < 2 {
			continue
		}
		idx, err := strconv.Atoi(strings.TrimSpace(parts[0]))
		if err != nil {
			continue
		}
		bdf := normalizeTopoBDF(strings.TrimSpace(parts[1]))
		if bdf == "" {
			continue
		}
		result[bdf] = idx
	}
	return result, nil
}

// normalizeTopoBDF normalizes a PCI bus address to "dddd:bb:dd.f" form so
// nvidia-smi's "pci.bus_id" output can be matched against
// HardwarePCIeDevice.Slot regardless of minor formatting differences
// (case, leading domain padding).
func normalizeTopoBDF(bdf string) string {
	bdf = strings.ToLower(strings.TrimSpace(bdf))
	if bdf == "" {
		return ""
	}
	parts := strings.Split(bdf, ":")
	if len(parts) == 3 {
		domain := parts[0]
		if len(domain) > 4 {
			domain = domain[len(domain)-4:]
		}
		return domain + ":" + parts[1] + ":" + parts[2]
	}
	return bdf
}

// ---------------------------------------------------------------------------
// Card status aggregation
//
// Every card on this page — whether it represents one component (CPU 1) or a
// group of identical ones (GPU ×4) — is colored as a whole by its worst
// observed status, with a plain-text summary as the card's last line
// (e.g. "4 OK" or "3 OK, 1 Warning"). There is no separate status chip: a
// chip needs its own fill, and the SVG boxes previously colored that chip
// via CSS classes written for HTML (.badge-ok sets `background`/`color`,
// which do nothing on an SVG <rect>/<text> — only `fill` does), so every
// chip rendered with the SVG default fill of solid black. Coloring the card
// itself uses real `fill:var(--ok-bg)` etc. declarations, which sidesteps
// that class entirely.
// ---------------------------------------------------------------------------

// classifyTopoSeverity converts a component's Status pointer to a severity
// rank (0=unknown, 1=OK, 2=Warning, 3=Critical), treating nil/unrecognized
// the same as "Unknown" — matches topoStatusBadgeClass's classification.
func classifyTopoSeverity(status *string) int {
	if status == nil {
		return 0
	}
	switch strings.ToUpper(strings.TrimSpace(*status)) {
	case "OK":
		return 1
	case "WARNING", "WARN", "PARTIAL":
		return 2
	case "CRITICAL", "FAIL", "FAILED", "ERROR":
		return 3
	default:
		return 0
	}
}

// topoSeverityColors returns the (fill, stroke, text) CSS var() triple a
// whole card is painted with for a given worst-observed severity.
func topoSeverityColors(sev int) (fill, stroke, text string) {
	switch sev {
	case 3:
		return "var(--crit-bg)", "var(--crit-border)", "var(--crit-fg)"
	case 2:
		return "var(--warn-bg)", "#c9ba9b", "var(--warn-fg)"
	case 1:
		return "var(--ok-bg)", "#a3c293", "var(--ok-fg)"
	default:
		return "var(--surface-2)", "var(--border)", "var(--muted)"
	}
}

// topoStatusTally counts how many components in a group fall into each
// severity bucket, so a group card can report "3 OK, 1 Warning" rather than
// collapsing to a single worst-of value and losing the rest.
type topoStatusTally struct {
	unknown, ok, warn, crit int
}

func (t *topoStatusTally) add(sev int) {
	switch sev {
	case 3:
		t.crit++
	case 2:
		t.warn++
	case 1:
		t.ok++
	default:
		t.unknown++
	}
}

func (t topoStatusTally) total() int { return t.unknown + t.ok + t.warn + t.crit }

func (t topoStatusTally) worst() int {
	switch {
	case t.crit > 0:
		return 3
	case t.warn > 0:
		return 2
	case t.ok > 0:
		return 1
	default:
		return 0
	}
}

// line renders the card's last-line status summary.
func (t topoStatusTally) line() string {
	if t.total() == 0 {
		return "No data"
	}
	if t.total() == 1 {
		switch {
		case t.crit > 0:
			return "Critical"
		case t.warn > 0:
			return "Warning"
		case t.ok > 0:
			return "OK"
		default:
			return "Unknown"
		}
	}
	var parts []string
	if t.crit > 0 {
		parts = append(parts, fmt.Sprintf("%d Critical", t.crit))
	}
	if t.warn > 0 {
		parts = append(parts, fmt.Sprintf("%d Warning", t.warn))
	}
	if t.ok > 0 {
		parts = append(parts, fmt.Sprintf("%d OK", t.ok))
	}
	if t.unknown > 0 {
		parts = append(parts, fmt.Sprintf("%d Unknown", t.unknown))
	}
	return strings.Join(parts, ", ")
}

// topoCardInfo is the shared visual content for one card, rendered either as
// an absolutely-positioned SVG box (main diagram) or an HTML flex item
// (Memory/Power Supplies rows) by the two writers below.
type topoCardInfo struct {
	label      string // e.g. "CPU 1", "GPU", "Power Supplies"
	sublabel   string // representative model/description, "" to omit
	count      int    // components represented by this card; >1 draws a stack
	statusLine string // last line of card text, e.g. "4 OK, 1 Warning"
	fillVar    string
	strokeVar  string
	textVar    string
	detailType string // "" = not clickable
}

// topoStackLayers returns how many faint backing cards to draw behind the
// front card to read as "a stack of N", capped at 2 — enough to signal
// "more than one" without the deck becoming its own visual clutter.
func topoStackLayers(count int) int {
	if count <= 1 {
		return 0
	}
	if count-1 > 2 {
		return 2
	}
	return count - 1
}

// ---------------------------------------------------------------------------
// Main topology diagram
// ---------------------------------------------------------------------------

const (
	topoBoxHeight = 70
	topoDeviceGap = 14
	topoTopMargin = 30
	topoStackStep = 4 // px offset per backing layer in the card-stack effect
)

type topoBox struct {
	x, y, w, h int
	topoCardInfo
}

type topoEdge struct {
	x1, y1, x2, y2 int
	color          string
}