## nimpak/remote/publisher.nim
## Package publishing and distribution system for NimPak
##
## This module implements secure package publishing with:
## - Package upload with signature generation
## - Delta upload system using CAS for efficient synchronization
## - Manifest generation with trust score propagation
## - Server-side trust policy validation
## - Integration with provenance tracking and audit trails

import std/[os, times, json, tables, strutils, strformat, httpclient, options]

type
  PublishingMode* = enum
    PublishFull = "full"           # Upload complete package
    PublishDelta = "delta"         # Upload only changes
    PublishMetadata = "metadata"   # Upload only metadata

  PackageUpload* = object
    packageName*: string
    version*: string
    packageData*: seq[byte]
    metadata*: JsonNode
    signature*: Option[string]
    provenance*: Option[JsonNode]
    binaries*: Table[string, BinaryUpload]
    mode*: PublishingMode

  BinaryUpload* = object
    platform*: string
    binaryData*: seq[byte]
    compatibility*: JsonNode
    metadata*: JsonNode
    signature*: Option[string]

  DeltaUpload* = object
    baseHash*: string
    targetHash*: string
    deltaData*: seq[byte]
    deltaSize*: int64
    compressionRatio*: float

  PublishingResult*[T] = object
    case success*: bool
    of true:
      value*: T
    of false:
      error*: string
      errorCode*: int
      validationErrors*: seq[string]

  UploadResult* = object
    packageHash*: string
    uploadSize*: int64
    deltaInfo*: Option[DeltaUpload]
    manifestUrl*: string
    trustScore*: float

  Repository* = object
    id*: string
    name*: string
    url*: string
    keyId*: string

  PackagePublisher* = object
    config*: PublisherConfig

  PublisherConfig* = object
    enableDeltaUploads*: bool
    enableCompression*: bool
    compressionLevel*: int
    maxUploadSize*: int64
    requireSignatures*: bool
    enableProvenanceTracking*: bool
    validateTrustPolicies*: bool
    chunkSize*: int

# =============================================================================
# Publisher Initialization
# =============================================================================

proc getDefaultPublisherConfig*(): PublisherConfig =
  ## Get default publisher configuration
  PublisherConfig(
    enableDeltaUploads: true,
    enableCompression: true,
    compressionLevel: 6,
    maxUploadSize: 1024 * 1024 * 1024,  # 1GB
    requireSignatures: false,
    enableProvenanceTracking: true,
    validateTrustPolicies: true,
    chunkSize: 64 * 1024
  )

proc newPackagePublisher*(): PackagePublisher =
  ## Create a new package publisher
  PackagePublisher(
    config: getDefaultPublisherConfig()
  )

proc getDefaultPublisherConfig*(): PublisherConfig =
  ## Get default publisher configuration
  PublisherConfig(
    enableDeltaUploads: true,
    enableCompression: true,
    compressionLevel: 6,
    maxUploadSize: 1024 * 1024 * 1024,  # 1GB
    requireSignatures: false,
    enableProvenanceTracking: true,
    validateTrustPolicies: true,
    chunkSize: 64 * 1024
  )

# =============================================================================
# Forward declarations
# =============================================================================

proc generatePackageSignature*(publisher: PackagePublisher, upload: PackageUpload): PublishingResult[string]
proc trackPackageProvenance*(packageName: string, version: string): Option[JsonNode]
proc calculateSimilarity*(data1: seq[byte], data2: seq[byte]): float
proc createDeltaPatch*(baseData: seq[byte], targetData: seq[byte]): seq[byte]
proc generateProvenanceAuditTrail*(provenance: JsonNode): JsonNode
proc uploadFullPackage*(publisher: PackagePublisher, repo: Repository,
                       upload: PackageUpload, uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult]
proc uploadDeltaPackage*(publisher: PackagePublisher, repo: Repository,
                        upload: PackageUpload, uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult]
proc uploadMetadataOnly*(publisher: PackagePublisher, repo: Repository,
                        upload: PackageUpload, uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult]
proc uploadPackageChunked*(publisher: PackagePublisher, repo: Repository,
                          upload: PackageUpload, packageData: seq[byte],
                          uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult]
proc uploadPackageSingle*(publisher: PackagePublisher, repo: Repository,
                         upload: PackageUpload, packageData: seq[byte],
                         uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult]
proc compressPackageData*(data: seq[byte], level: int): seq[byte]

# =============================================================================
# Package Preparation
# =============================================================================

proc preparePackageUpload*(publisher: PackagePublisher, packagePath: string,
                          metadata: JsonNode, mode: PublishingMode = PublishFull): PublishingResult[UploadResult] =
  ## Prepare package for upload
  try:
    if not fileExists(packagePath):
      return PublishingResult[UploadResult](success: false, error: "Package file not found", errorCode: 404)

    # Read package data
    let packageContent = readFile(packagePath)
    var packageBytes = newSeq[byte](packageContent.len)
    for i, c in packageContent:
      packageBytes[i] = c.byte

    # Validate package size
    if packageBytes.len.int64 > publisher.config.maxUploadSize:
      return PublishingResult[UploadResult](success: false, error: "Package exceeds maximum upload size", errorCode: 413)

    # Calculate package hash (simplified)
    let packageHash = fmt"blake3-{packageBytes.len}-{packageContent[0..min(7, packageContent.len-1)]}"

    # Create package upload
    var upload = PackageUpload(
      packageName: metadata["name"].getStr(),
      version: metadata["version"].getStr(),
      packageData: packageBytes,
      metadata: metadata,
      signature: none(string),
      provenance: none(JsonNode),
      binaries: initTable[string, BinaryUpload](),
      mode: mode
    )

    # Generate signature if required
    if publisher.config.requireSignatures:
      let signResult = publisher.generatePackageSignature(upload)
      if not signResult.success:
        return PublishingResult[UploadResult](success: false, error: signResult.error, errorCode: signResult.errorCode)
      upload.signature = some(signResult.value)

    # Add provenance if enabled
    if publisher.config.enableProvenanceTracking:
      let provenanceOpt = trackPackageProvenance(metadata["name"].getStr(), metadata["version"].getStr())
      if provenanceOpt.isSome():
        upload.provenance = provenanceOpt

    let result = UploadResult(
      packageHash: packageHash,
      uploadSize: packageBytes.len.int64,
      deltaInfo: none(DeltaUpload),
      manifestUrl: "",
      trustScore: 0.5
    )

    return PublishingResult[UploadResult](success: true, value: result)

  except Exception as e:
    return PublishingResult[UploadResult](success: false, error: fmt"Package preparation failed: {e.msg}", errorCode: 500)

proc generatePackageSignature*(publisher: PackagePublisher, upload: PackageUpload): PublishingResult[string] =
  ## Generate signature for package upload
  try:
    # TODO: Implement actual signature generation when crypto is available
    # For now, create a placeholder signature
    let signature = fmt"ed25519-{upload.packageName}-{upload.version}-{now().toTime().toUnix()}"

    echo fmt"Package signature generated: {upload.packageName} v{upload.version}"

    return PublishingResult[string](success: true, value: signature)

  except Exception as e:
    return PublishingResult[string](success: false, error: fmt"Signature generation failed: {e.msg}", errorCode: 500)

proc trackPackageProvenance*(packageName: string, version: string): Option[JsonNode] =
  ## Track package provenance (placeholder implementation)
  # TODO: Implement actual provenance tracking
  return none(JsonNode)

# =============================================================================
# Delta Upload System
# =============================================================================

proc calculateDelta*(publisher: PackagePublisher, baseData: seq[byte],
                    targetData: seq[byte]): DeltaUpload =
  ## Calculate delta between two package versions
  try:
    # Calculate hashes (simplified)
    let baseHash = fmt"blake3-{baseData.len}-base"
    let targetHash = fmt"blake3-{targetData.len}-target"

    # TODO: Implement actual delta calculation (binary diff)
    # For now, use simple approach - if files are similar enough, create delta
    let similarity = calculateSimilarity(baseData, targetData)

    if similarity > 0.3:  # 30% similarity threshold
      # Create delta (placeholder implementation)
      let deltaData = createDeltaPatch(baseData, targetData)
      let compressionRatio = deltaData.len.float / targetData.len.float

      return DeltaUpload(
        baseHash: baseHash,
        targetHash: targetHash,
        deltaData: deltaData,
        deltaSize: deltaData.len.int64,
        compressionRatio: compressionRatio
      )
    else:
      # Not worth creating delta - too different
      return DeltaUpload(
        baseHash: baseHash,
        targetHash: targetHash,
        deltaData: @[],
        deltaSize: 0,
        compressionRatio: 1.0
      )

  except Exception:
    # Return empty delta on error
    return DeltaUpload(
      baseHash: "",
      targetHash: "",
      deltaData: @[],
      deltaSize: 0,
      compressionRatio: 1.0
    )

proc calculateSimilarity*(data1: seq[byte], data2: seq[byte]): float =
  ## Calculate similarity between two byte sequences
  if data1.len == 0 and data2.len == 0:
    return 1.0

  if data1.len == 0 or data2.len == 0:
    return 0.0

  # Simple similarity calculation based on common bytes
  let minLen = min(data1.len, data2.len)
  var commonBytes = 0

  for i in 0..<minLen:
    if data1[i] == data2[i]:
      commonBytes += 1

  return commonBytes.float / max(data1.len, data2.len).float

proc createDeltaPatch*(baseData: seq[byte], targetData: seq[byte]): seq[byte] =
  ## Create delta patch (placeholder implementation)
  # TODO: Implement actual binary diff algorithm (bsdiff, xdelta, etc.)
  # For now, return a simple diff representation
  var delta: seq[byte] = @[]

  # Add header
  let header = fmt"DELTA:{baseData.len}:{targetData.len}:"
  for c in header:
    delta.add(c.byte)

  # Add simple diff data (placeholder)
  let diffSize = min(1024, abs(targetData.len - baseData.len))
  for i in 0..<diffSize:
    delta.add((i mod 256).byte)

  return delta

proc applyDeltaPatch*(baseData: seq[byte], deltaData: seq[byte]): seq[byte] =
  ## Apply delta patch to base data (placeholder implementation)
  # TODO: Implement actual delta application
  # For now, return base data (no-op)
  return baseData

# =============================================================================
# Trust Score Calculation
# =============================================================================

proc calculateUploadTrustScore*(publisher: PackagePublisher, upload: PackageUpload): float =
  ## Calculate trust score for package upload
  var score = 0.5  # Base score

  # Signature bonus
  if upload.signature.isSome():
    score += 0.2

  # Provenance bonus
  if upload.provenance.isSome():
    score += 0.3

  # Metadata completeness bonus
  if upload.metadata.hasKey("description") and upload.metadata["description"].getStr() != "":
    score += 0.05
  if upload.metadata.hasKey("license") and upload.metadata["license"].getStr() != "":
    score += 0.05

  # Binary availability bonus
  if upload.binaries.len > 0:
    score += 0.1

  return min(1.0, score)

# =============================================================================
# Server-Side Validation
# =============================================================================

proc validateUpload*(publisher: PackagePublisher, upload: PackageUpload): tuple[valid: bool, errors: seq[string]] =
  ## Validate package upload against policies
  var errors: seq[string] = @[]

  # Basic validation
  if upload.packageName == "":
    errors.add("Package name is required")

  if upload.version == "":
    errors.add("Package version is required")

  if upload.packageData.len == 0:
    errors.add("Package data is empty")

  # Size validation
  if upload.packageData.len.int64 > publisher.config.maxUploadSize:
    errors.add(fmt"Package size exceeds limit: {upload.packageData.len} bytes")

  # Signature validation
  if publisher.config.requireSignatures and upload.signature.isNone():
    errors.add("Package signature is required")

  return (errors.len == 0, errors)

# =============================================================================
# Package Upload
# =============================================================================

proc uploadPackage*(publisher: PackagePublisher, repositoryId: string,
                   upload: PackageUpload): PublishingResult[UploadResult] =
  ## Upload package to repository
  try:
    # Create mock repository
    let repo = Repository(
      id: repositoryId,
      name: "Mock Repository",
      url: "https://packages.nexusos.org",
      keyId: "repo-key-2025"
    )

    # Validate upload
    let (valid, validationErrors) = publisher.validateUpload(upload)
    if not valid:
      return PublishingResult[UploadResult](success: false, error: "Upload validation failed",
                            errorCode: 400, validationErrors: validationErrors)

    # Calculate trust score
    let trustScore = publisher.calculateUploadTrustScore(upload)

    # Prepare upload data
    var uploadData = %*{
      "package_name": upload.packageName,
      "version": upload.version,
      "metadata": {
        "description": upload.metadata.getOrDefault("description").getStr(""),
        "size": upload.packageData.len,
        "trust_score": trustScore
      }
    }

    # Add signature if present
    if upload.signature.isSome():
      let sig = upload.signature.get()
      uploadData["signature"] = %*{
        "signature": sig,
        "timestamp": $now()
      }

    # Add provenance if present
    if upload.provenance.isSome():
      let provenance = upload.provenance.get()
      uploadData["provenance"] = generateProvenanceAuditTrail(provenance)

    # Determine upload method
    case upload.mode:
    of PublishFull:
      return publisher.uploadFullPackage(repo, upload, uploadData, trustScore)
    of PublishDelta:
      return publisher.uploadDeltaPackage(repo, upload, uploadData, trustScore)
    of PublishMetadata:
      return publisher.uploadMetadataOnly(repo, upload, uploadData, trustScore)

  except Exception as e:
    return PublishingResult[UploadResult](success: false, error: fmt"Upload failed: {e.msg}", errorCode: 500)

proc generateProvenanceAuditTrail*(provenance: JsonNode): JsonNode =
  ## Generate provenance audit trail
  return %*{
    "package_id": provenance.getOrDefault("package_id").getStr(""),
    "version": provenance.getOrDefault("version").getStr(""),
    "trust_score": provenance.getOrDefault("trust_score").getFloat(0.5),
    "step_count": provenance.getOrDefault("steps").getElems().len,
    "verification_errors": provenance.getOrDefault("verification_errors").getElems().len
  }

proc uploadFullPackage*(publisher: PackagePublisher, repo: Repository,
                       upload: PackageUpload, uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult] =
  ## Upload complete package
  try:
    # Compress package data if enabled
    let finalData = if publisher.config.enableCompression:
      compressPackageData(upload.packageData, publisher.config.compressionLevel)
    else:
      upload.packageData

    # Upload in chunks if large
    if finalData.len > publisher.config.chunkSize * 10:
      return publisher.uploadPackageChunked(repo, upload, finalData, uploadData, trustScore)
    else:
      return publisher.uploadPackageSingle(repo, upload, finalData, uploadData, trustScore)

  except Exception as e:
    return PublishingResult[UploadResult](success: false, error: fmt"Full upload failed: {e.msg}", errorCode: 500)

proc uploadPackageSingle*(publisher: PackagePublisher, repo: Repository,
                         upload: PackageUpload, packageData: seq[byte],
                         uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult] =
  ## Upload package in single request
  try:
    # Mock successful upload
    let packageHash = fmt"blake3-{packageData.len}-uploaded"
    let manifestUrl = fmt"{repo.url}/manifests/{upload.packageName}-{upload.version}.json"

    echo fmt"Package uploaded successfully: {upload.packageName} v{upload.version}"

    let result = UploadResult(
      packageHash: packageHash,
      uploadSize: packageData.len.int64,
      deltaInfo: none(DeltaUpload),
      manifestUrl: manifestUrl,
      trustScore: trustScore
    )

    return PublishingResult[UploadResult](success: true, value: result)

  except Exception as e:
    return PublishingResult[UploadResult](success: false, error: fmt"Single upload failed: {e.msg}", errorCode: 500)

proc uploadPackageChunked*(publisher: PackagePublisher, repo: Repository,
                          upload: PackageUpload, packageData: seq[byte],
                          uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult] =
  ## Upload package using chunked upload
  try:
    let chunkSize = publisher.config.chunkSize
    let totalChunks = (packageData.len + chunkSize - 1) div chunkSize

    # Mock chunked upload process
    let uploadId = fmt"upload-{upload.packageName}-{now().toTime().toUnix()}"

    # Simulate chunk upload
    for chunkIndex in 0..<totalChunks:
      let startPos = chunkIndex * chunkSize
      let endPos = min(startPos + chunkSize, packageData.len)
      # In real implementation, would upload chunk data here

    # Mock successful completion
    let packageHash = fmt"blake3-{packageData.len}-chunked"
    let manifestUrl = fmt"{repo.url}/manifests/{upload.packageName}-{upload.version}.json"

    echo fmt"Chunked package upload completed: {upload.packageName} v{upload.version} ({totalChunks} chunks)"

    let result = UploadResult(
      packageHash: packageHash,
      uploadSize: packageData.len.int64,
      deltaInfo: none(DeltaUpload),
      manifestUrl: manifestUrl,
      trustScore: trustScore
    )

    return PublishingResult[UploadResult](success: true, value: result)

  except Exception as e:
    return PublishingResult[UploadResult](success: false, error: fmt"Chunked upload failed: {e.msg}", errorCode: 500)

proc uploadDeltaPackage*(publisher: PackagePublisher, repo: Repository,
                        upload: PackageUpload, uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult] =
  ## Upload package using delta compression
  try:
    # TODO: Implement delta upload
    # For now, fall back to full upload
    return publisher.uploadFullPackage(repo, upload, uploadData, trustScore)

  except Exception as e:
    return PublishingResult[UploadResult](success: false, error: fmt"Delta upload failed: {e.msg}", errorCode: 500)

proc uploadMetadataOnly*(publisher: PackagePublisher, repo: Repository,
                        upload: PackageUpload, uploadData: JsonNode, trustScore: float): PublishingResult[UploadResult] =
  ## Upload only package metadata
  try:
    # Mock metadata upload
    let manifestUrl = fmt"{repo.url}/manifests/{upload.packageName}-{upload.version}.json"

    let result = UploadResult(
      packageHash: "",
      uploadSize: 0,
      deltaInfo: none(DeltaUpload),
      manifestUrl: manifestUrl,
      trustScore: trustScore
    )

    return PublishingResult[UploadResult](success: true, value: result)

  except Exception as e:
    return PublishingResult[UploadResult](success: false, error: fmt"Metadata upload failed: {e.msg}", errorCode: 500)

# =============================================================================
# Compression Support
# =============================================================================

proc compressPackageData*(data: seq[byte], level: int): seq[byte] =
  ## Compress package data
  # TODO: Implement actual compression (zstd, lz4, etc.)
  # For now, return original data
  return data

proc decompressPackageData*(data: seq[byte]): seq[byte] =
  ## Decompress package data
  # TODO: Implement actual decompression
  # For now, return original data
  return data

# =============================================================================
# Export main functions
# =============================================================================

export PublishingMode, PackageUpload, BinaryUpload, DeltaUpload
export PublishingResult, UploadResult, PackagePublisher, PublisherConfig
export newPackagePublisher, getDefaultPublisherConfig
export preparePackageUpload, generatePackageSignature
export calculateDelta, calculateSimilarity, createDeltaPatch, applyDeltaPatch
export calculateUploadTrustScore, validateUpload
export uploadPackage, uploadFullPackage, uploadDeltaPackage, uploadMetadataOnly
export compressPackageData, decompressPackageData