defmodule Paraxial.Scan do
  @moduledoc false

  alias Paraxial.Finding

  def get_timestamp() do
    DateTime.utc_now()
  end

  def make_license(license_scan) do
    license_scan
    |> Enum.map(fn [dep, version, license] ->
      %Finding{
        source: "license_scan",
        content: %{
          "dependency" => dep,
          "version" => version,
          "license" => license,
          "reason" => "GPL software is not allowed for this site."
        }
      }
    end)
  end

  def make_sobelow(raw_scan) do
    # Input: The raw json output from a sobelow scan
    # Action: Use Jason (it's already in project) to parse, construct findings
    # Returns a list of findings
    case Jason.decode(raw_scan) do
      {:ok, scan_map} ->
        sobelow_get_findings(scan_map)

      {:error, _e} ->
        # Umbrella app
        many_scans = String.split(raw_scan, "\n\n") |> tl()

        Enum.map(many_scans, fn one_scan ->
          string_json = String.split(one_scan, "\n==>") |> hd()

          case Jason.decode(string_json) do
            {:ok, scan_map} ->
              sobelow_get_findings(scan_map)

            _ ->
              []
          end
        end)
        |> List.flatten()
    end
  end

  def sobelow_get_findings(scan_map) do
    # Input: The sobelow map like %{"findings" => %{"high_confidence" => ...}}
    # Output: A list of findings
    Enum.map(scan_map["findings"], fn {confidence, findings} ->
      Enum.map(findings, fn finding ->
        %Finding{
          source: "sobelow",
          content: Map.put(finding, "confidence", confidence)
        }
      end)
    end)
    |> List.flatten()
  end

  def make_deps(raw_deps, ignore \\ nil) do
    raw_deps
    |> String.split("\n\n")
    |> Enum.map(&dep_to_finding/1)
    |> List.flatten()
    |> filter_deps(ignore)
    |> Enum.filter(fn finding -> severity_exists?(finding) end)
  end

  # Advisory IDs as printed by hex.audit and deps.audit, e.g.
  # CVE-2026-32687, EEF-CVE-2026-43969, GHSA-p8f7-22gq-m7j9
  @vuln_id_regex ~r/^(EEF-CVE|CVE|GHSA)-/i

  def read_ignore_file() do
    if File.exists?("./.paraxial-ignore-deps") do
      parse_ignore_lines(File.read!("./.paraxial-ignore-deps"))
    else
      nil
    end
  end

  # Parses the contents of .paraxial-ignore-deps. Valid lines:
  #   hackney                    -> ignore the entire dependency
  #   postgrex CVE-2026-32687    -> ignore one vulnerability of one dependency
  # Blank lines and lines starting with # are skipped. Anything else is
  # collected under :malformed so the scan task can warn about it.
  def parse_ignore_lines(raw) do
    raw
    |> String.split("\n")
    |> Enum.map(&String.trim/1)
    |> Enum.reject(&(&1 == "" or String.starts_with?(&1, "#")))
    |> Enum.reduce(%{deps: [], vulns: [], malformed: []}, fn line, acc ->
      case String.split(line, " ", trim: true) do
        [dep] ->
          if vuln_id?(dep) do
            %{acc | malformed: acc.malformed ++ [line]}
          else
            %{acc | deps: acc.deps ++ [dep]}
          end

        [dep, vuln] ->
          if vuln_id?(vuln) and not vuln_id?(dep) do
            %{acc | vulns: acc.vulns ++ [{dep, vuln}]}
          else
            %{acc | malformed: acc.malformed ++ [line]}
          end

        _ ->
          %{acc | malformed: acc.malformed ++ [line]}
      end
    end)
  end

  defp vuln_id?(token), do: Regex.match?(@vuln_id_regex, token)

  # Builds ignore entries from hex's ignore_advisories / ignore_retirements
  # settings (hex >= 2.5.1), so findings the user acknowledged for hex.audit
  # are also not reported by paraxial, including the same advisories found
  # via deps.audit and hex versions that predate the settings.
  #
  # Sources, in hex's order of precedence: the HEX_IGNORE_ADVISORIES /
  # HEX_IGNORE_RETIREMENTS environment variables (comma-separated,
  # retirements as NAME or NAME@VERSION), then the :hex key of the project
  # config. Returns nil when nothing is configured.
  def read_hex_ignores() do
    hex_config =
      case Mix.Project.config()[:hex] do
        config when is_list(config) -> config
        _ -> []
      end

    parse_hex_ignores(
      hex_config,
      System.get_env("HEX_IGNORE_ADVISORIES"),
      System.get_env("HEX_IGNORE_RETIREMENTS")
    )
  end

  # Advisory entries are ID strings, matched against a finding's primary ID
  # and aka aliases. Retirement entries are {name, version} tuples where a
  # nil version matches every version of the package, same as hex. A set env
  # var takes precedence over the project config unless it is empty
  # (skip_env_if_empty in Hex.State). Entries hex would reject as invalid
  # are skipped.
  def parse_hex_ignores(hex_config, env_advisories \\ nil, env_retirements \\ nil) do
    env_advisory_ids = split_env_list(env_advisories)

    advisory_ids =
      if env_advisory_ids != [] do
        env_advisory_ids
      else
        hex_config
        |> config_list(:ignore_advisories)
        |> Enum.filter(&(is_binary(&1) and &1 != ""))
      end

    env_retirement_entries =
      env_retirements |> split_env_list() |> Enum.flat_map(&parse_env_retirement/1)

    retirements =
      if env_retirement_entries != [] do
        env_retirement_entries
      else
        hex_config
        |> config_list(:ignore_retirements)
        |> Enum.flat_map(&parse_config_retirement/1)
      end

    if advisory_ids == [] and retirements == [] do
      nil
    else
      %{advisory_ids: advisory_ids, retirements: retirements}
    end
  end

  defp config_list(config, key) do
    case config[key] do
      list when is_list(list) -> list
      _ -> []
    end
  end

  defp split_env_list(nil), do: []

  defp split_env_list(value) do
    value
    |> String.split(",")
    |> Enum.map(&String.trim/1)
    |> Enum.reject(&(&1 == ""))
  end

  # "decimal" or "phoenix@1.0.0"
  defp parse_env_retirement(entry) do
    case String.split(entry, "@", parts: 2) do
      [name] -> [{name, nil}]
      [name, version] when name != "" and version != "" -> [{name, version}]
      _ -> []
    end
  end

  # :decimal or {:phoenix, "1.0.0"} in mix.exs
  defp parse_config_retirement(name) when is_atom(name) and name not in [nil, true, false],
    do: [{Atom.to_string(name), nil}]

  defp parse_config_retirement({name, version})
       when is_atom(name) and name not in [nil, true, false] and is_binary(version),
       do: [{Atom.to_string(name), version}]

  defp parse_config_retirement(_), do: []

  # Combines the .paraxial-ignore-deps ignores with the hex config ignores
  # into one map the filter functions accept.
  def merge_ignores(nil, nil), do: nil

  def merge_ignores(file_ignore, hex_ignore) do
    %{deps: [], vulns: [], malformed: [], advisory_ids: [], retirements: []}
    |> Map.merge(file_ignore || %{})
    |> Map.merge(hex_ignore || %{})
  end

  def filter_deps(deps_list, nil), do: deps_list

  def filter_deps(deps_list, ignore) do
    ig = downcase_ignore(ignore)

    Enum.reject(deps_list, fn finding ->
      name = finding.content["Name"] |> to_string() |> String.trim() |> String.downcase()
      cve = finding.content["CVE"] |> to_string() |> String.downcase()
      url = finding.content["URL"] |> to_string() |> String.downcase()

      name in ig.deps or
        Enum.any?(ig.vulns, fn {dep, vuln} ->
          dep == name and (vuln == cve or String.contains?(url, vuln))
        end) or
        Enum.any?(ig.advisory_ids, fn id -> id == cve or String.contains?(url, id) end)
    end)
  end

  def filter_hex(findings, nil), do: findings

  def filter_hex(findings, ignore) do
    ig = downcase_ignore(ignore)

    Enum.reject(findings, fn finding ->
      name = finding.content["dependency"] |> to_string() |> String.downcase()

      ids =
        [finding.content["cve_id"] | Map.get(finding.content, "aka", [])]
        |> Enum.reject(&is_nil/1)
        |> Enum.map(&String.downcase/1)

      name in ig.deps or
        Enum.any?(ig.vulns, fn {dep, vuln} -> dep == name and vuln in ids end) or
        Enum.any?(ig.advisory_ids, &(&1 in ids)) or
        retirement_ignored?(finding, name, ig.retirements)
    end)
  end

  # Mirrors hex's ignore_retirements matching: applies only to retired
  # findings (never advisories, even for the same package), a nil version
  # matches every version of the package.
  defp retirement_ignored?(finding, name, retirements) do
    finding.content["hex_type"] != "advisory" and
      Enum.any?(retirements, fn
        {^name, nil} -> true
        {^name, pinned} -> finding.content["version"] == pinned
        _ -> false
      end)
  end

  defp downcase_ignore(ignore) do
    %{
      deps: Enum.map(Map.get(ignore, :deps, []), &String.downcase/1),
      vulns:
        Enum.map(Map.get(ignore, :vulns, []), fn {d, v} ->
          {String.downcase(d), String.downcase(v)}
        end),
      advisory_ids: Enum.map(Map.get(ignore, :advisory_ids, []), &String.downcase/1),
      retirements:
        Enum.map(Map.get(ignore, :retirements, []), fn {n, v} -> {String.downcase(n), v} end)
    }
  end

  defp severity_exists?(fmap) do
    Enum.any?(Map.keys(fmap.content), fn key ->
      String.downcase(key) == "severity"
    end)
  end

  def fpart_to_tuple(fpart) do
    fpart
    |> String.split(":", parts: 2)
    |> List.to_tuple()
  end

  def dep_to_finding(dep_string) do
    finding = String.split(dep_string, "\n", trim: true)

    if length(finding) <= 2 do
      []
    else
      fmap =
        finding
        |> Enum.map(&fpart_to_tuple/1)
        # On some Elixir apps compilation metadata shows up here as tuples of 1
        # Filter out tuples that do not equal length 2 to avoid errors
        |> Enum.filter(fn tup -> tuple_size(tup) == 2 end)
        |> Map.new()

      %Finding{
        source: "deps.audit",
        content: fmap
      }
    end
  end

  def print_findings(findings) do
    Enum.map(findings, fn finding ->
      IO.puts("[Paraxial] #{finding.source}")
      Enum.each(Map.to_list(finding.content), fn {label, line} ->
        IO.puts("  #{label}: #{line}")
      end)
      IO.puts("")
    end)
  end

  # Input: Raw output from mix hex.audit
  # Returns a list of findings
  def make_hex(raw_hex, ignore \\ nil)
  def make_hex("No retired packages found\n", _ignore), do: []
  def make_hex("No retired packages found\nNo advisories found\n", _ignore), do: []
  # Hex >= 2.5.1 all-clear message; may be followed by unused-ignore warnings,
  # which Hex prints to stdout.
  def make_hex("No retired or security advisory packages found" <> _rest, _ignore), do: []

  def make_hex(raw_hex, ignore) do
    {active_hex, had_ignored_section} = strip_hex_ignored_sections(raw_hex)

    findings =
      if had_ignored_section or String.contains?(active_hex, "Retired:\n") or
           String.contains?(active_hex, "Advisories:\n") do
        make_hex_new(active_hex)
      else
        make_hex_old(active_hex)
      end

    filter_hex(findings, ignore)
  end

  # Hex >= 2.5.1 prints findings acknowledged via the ignore_advisories /
  # ignore_retirements mix.exs config in "Ignored retired:" and
  # "Ignored advisories:" sections after the active ones, without failing the
  # audit. Drop everything from the first ignored section onward so those
  # entries are never parsed as findings, and so ignored-only output (which
  # has no Retired:/Advisories: header) still routes to the hex >= 2.5 parser.
  defp strip_hex_ignored_sections(raw_hex) do
    case String.split(raw_hex, ~r/^Ignored (?:retired|advisories):\n/m, parts: 2) do
      [active, _ignored] -> {active, true}
      [_] -> {raw_hex, false}
    end
  end

  # Parses the old hex.audit format (hex < 2.5.0):
  #   Dependency  Version  Retirement reason
  #   mojito      0.7.12   (deprecated) ...
  defp make_hex_old(raw_hex) do
    raw_lines = String.split(raw_hex, "\n", trim: true)
    raw_findings = tl(raw_lines)

    Enum.map(raw_findings, fn finding ->
      [dep, ver | reason] = String.split(finding, " ", trim: true)

      %Finding{
        source: "hex.audit",
        content: %{
          "dependency" => dep,
          "version" => ver,
          "reason" => Enum.join(reason, " ")
        }
      }
    end)
  end

  # Parses the new hex.audit format (hex >= 2.5.0) which has two sections:
  #
  # Retired:
  #   dep version - reason text
  #
  # Advisories:
  #   dep version - CVE-ID (SEVERITY)
  #     aka: alias1, alias2
  #     Description text
  #     https://url
  defp make_hex_new(raw_hex) do
    retired = parse_hex_retired_section(raw_hex)
    advisories = parse_hex_advisories_section(raw_hex)
    retired ++ advisories
  end

  defp parse_hex_retired_section(raw_hex) do
    case Regex.run(~r/Retired:\n(.*?)\n(?:Advisories:|\z)/s, raw_hex, capture: :all_but_first) do
      [block] ->
        block
        |> String.split("\n", trim: true)
        |> Enum.reject(&footer_line?/1)
        |> Enum.flat_map(fn line ->
          # "  dep version - reason text". Skip anything else, e.g. the
          # unused-ignore warnings hex >= 2.5.1 prints to stdout.
          case Regex.run(~r/^(\S+)\s+(\S+)\s+-\s+(.*)$/, String.trim(line)) do
            [_, dep, ver, reason] ->
              [%Finding{
                source: "hex.audit",
                content: %{
                  "dependency" => dep,
                  "version" => ver,
                  "reason" => reason,
                  "hex_type" => "retired"
                }
              }]

            nil ->
              []
          end
        end)

      nil ->
        []
    end
  end

  defp parse_hex_advisories_section(raw_hex) do
    case Regex.run(~r/Advisories:\n(.*)/s, raw_hex, capture: :all_but_first) do
      [block] ->
        block
        |> String.split("\n\n", trim: true)
        |> Enum.reject(fn chunk -> footer_line?(String.trim(chunk)) end)
        |> Enum.flat_map(&parse_hex_advisory_block/1)

      nil ->
        []
    end
  end

  defp parse_hex_advisory_block(block) do
    lines =
      block
      |> String.split("\n", trim: true)
      |> Enum.reject(&footer_line?/1)
      |> Enum.map(&String.trim/1)

    case lines do
      [header | _rest] ->
        # Header: "dep version - CVE-ID" or "dep version - CVE-ID (SEVERITY)"
        # Lines are: [header, "aka: ...", "Title text", "https://url"]
        title = Enum.at(lines, 2)

        case Regex.run(~r/^(\S+)\s+(\S+)\s+-\s+(\S+)(?:\s+\((\w+)\))?$/, header) do
          [_, dep, ver, cve_id, severity] ->
            [%Finding{
              source: "hex.audit",
              content: %{
                "dependency" => dep,
                "version" => ver,
                "cve_id" => cve_id,
                "severity" => if(severity == "", do: nil, else: severity),
                "title" => title,
                "url" => find_url_in_lines(lines),
                "aka" => find_aka_in_lines(lines),
                "hex_type" => "advisory"
              }
            }]

          [_, dep, ver, cve_id] ->
            # No (SEVERITY) suffix in header line
            [%Finding{
              source: "hex.audit",
              content: %{
                "dependency" => dep,
                "version" => ver,
                "cve_id" => cve_id,
                "severity" => nil,
                "title" => title,
                "url" => find_url_in_lines(lines),
                "aka" => find_aka_in_lines(lines),
                "hex_type" => "advisory"
              }
            }]

          _ ->
            []
        end

      _ ->
        []
    end
  end

  # Parses "aka: CVE-2026-43969, GHSA-g2wm-735q-3f56" into a list of IDs
  defp find_aka_in_lines(lines) do
    case Enum.find(lines, fn l -> String.starts_with?(l, "aka:") end) do
      nil ->
        []

      aka_line ->
        aka_line
        |> String.trim_leading("aka:")
        |> String.split(",")
        |> Enum.map(&String.trim/1)
        |> Enum.reject(&(&1 == ""))
    end
  end

  defp find_url_in_lines(lines) do
    Enum.find(lines, fn l -> String.starts_with?(l, "http") end)
  end

  defp footer_line?(line) do
    line == "Found retired packages" or
      line == "Found packages with security advisories" or
      line == "No advisories found" or
      line == "No retired packages found"
  end
end