package nvdmirror

import (
  "fmt"
  "time"
)

// Sync() configuration.
type SyncConfig struct {
  // CVE 1.1 Base URL.  The full meta and JSON URLs are constructed by
  // appending the file name to this base.
  Cve11BaseUrl string

  // CPE Match 1.0 base URL.  The full meta and JSON URLs are
  // constructed by appending the file name to this base.
  CpeMatch10BaseUrl string

  // CPE 2.3 dictionary URL.
  Cpe23DictUrl string

  // CISA known exploited vulnerabilities catalog (KEVC) URL.
  CisaKevcUrl string

  // Common Weakness Enumeration list URL.
  CweListUrl string

  // User agent string.  Set to "" for default user agent string.
  UserAgent string

  // Maximum number of idle connections.
	MaxIdleConns int

  // Idle connection timeout.
	IdleConnTimeout time.Duration
}

// Default configuration (NVD and CISA URLs).
var DefaultConfig = SyncConfig {
  Cve11BaseUrl: "https://nvd.nist.gov/feeds/json/cve/1.1",
  CpeMatch10BaseUrl: "https://nvd.nist.gov/feeds/json/cpematch/1.0",
  Cpe23DictUrl: "https://nvd.nist.gov/feeds/xml/cpe/dictionary/official-cpe-dictionary_v2.3.xml.gz",
  CisaKevcUrl: "https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json",
  CweListUrl: "https://cwe.mitre.org/data/xml/cwec_latest.xml.zip",
  UserAgent: "cvez/0.1.0",
}

// Initial (first) CVE year.
const baseYear = 2002

// Additional non-year CVE feeds.
var cveExtraFiles = []string {
  "modified",
  "recent",
}

// Get user agent string.
func (me SyncConfig) GetUserAgent() string {
  if len(me.UserAgent) > 0 {
    return me.UserAgent
  } else {
    return DefaultConfig.UserAgent
  }
}

// Get URL for CVE feed file.
func (me SyncConfig) GetCveUrl(id, ext string) string {
  return fmt.Sprintf("%s/nvdcve-1.1-%s.%s", me.Cve11BaseUrl, id, ext)
}

// Get URL for CVE feed file for given year.
func (me SyncConfig) GetCveYearUrl(year int, ext string) string {
  return me.GetCveUrl(fmt.Sprintf("%04d", year), ext)
}

// Get URL for CPE match file.
func (me SyncConfig) GetCpeMatchUrl(ext string) string {
  return fmt.Sprintf("%s/nvdcpematch-1.0.%s", me.CpeMatch10BaseUrl, ext)
}

// Get CPE dictionary URL.
func (me SyncConfig) GetCpeDictUrl() string {
  if len(me.Cpe23DictUrl) > 0 {
    return me.Cpe23DictUrl
  } else {
    return DefaultConfig.Cpe23DictUrl
  }
}

// Get CISA KEVC URL.
func (me SyncConfig) GetCisaKevcUrl() string {
  if len(me.CisaKevcUrl) > 0 {
    return me.CisaKevcUrl
  } else {
    return DefaultConfig.CisaKevcUrl
  }
}

// Get CWE list URL.
func (me SyncConfig) GetCweListUrl() string {
  if len(me.CweListUrl) > 0 {
    return me.CweListUrl
  } else {
    return DefaultConfig.CweListUrl
  }
}

// get map of meta URLs to possible meta updates.
func (me SyncConfig) getMetas() map[string]Update {
  // calculate total number of years
  numYears := time.Now().Year() - baseYear + 1

  r := make(map[string]Update)

  // fetch cve feed metas
  for i := 0; i < numYears; i++ {
    year := baseYear + i
    metaUrl := me.GetCveYearUrl(year, "meta")
    feedUrl := me.GetCveYearUrl(year, "json.gz")

    r[metaUrl] = Update {
      Type: UpdateCveYear,
      Year: baseYear + i,
      Url: feedUrl,
    }
  }

  // fetch cve extra file metas
  for _, s := range(cveExtraFiles) {
    metaUrl := me.GetCveUrl(s, "meta")
    feedUrl := me.GetCveUrl(s, "json.gz")
    r[metaUrl] = Update { Type: UpdateCveYear, Meta: s, Url: feedUrl }
  }

  {
    // add cpe match
    metaUrl := me.GetCpeMatchUrl("meta")
    feedUrl := me.GetCpeMatchUrl("json.gz")
    r[metaUrl] = Update { Type: UpdateCpeMatch, Url: feedUrl }
  }

  // return map
  return r
}