#! /bin/bash

main() {
   config
   for id in $(ids); do
      if should_crawl "$id"; then
         crawl "$id"
      fi
      rewrite "$id"
   done
}

config() {
   set -o pipefail
   set -e
   export CACHE="${CACHE:-"$(mktemp -d)"}"
   export CACHE_DURATION=$((60*5))
   export CRAWL_INTERVAL=$((60*5))
   export NOTEA_ADDR="${NOTEA_ADDR:-"http://localhost:3000"}"
   export GITLAB_PAT="$GITLAB_PAT"
}

log() {
   echo "$(date)> $*" >&2
}

ids() {
   notea ids
}

should_crawl() {
   local f="$CACHE/crawled.$1"
   if [ ! -f "$f" ]; then
      return 0
   fi
   local last_crawled=$(date -r "$f" +%s)
   local now=$(date +%s)
   if ((now-last_crawled < CRAWL_INTERVAL)); then
      return 0
   fi
   return 1
}

crawl() {
   local id="$1"
   local json="$(notea get "$id")"
   local content="$(echo "$json" | jq -r .content)"
   if ! is_crawlable "$content"; then
      return 0
   fi
   local crawlable_source="$(echo "$content" | head -n 1 | awk '{print $NF}')"
   for backend in gitlab; do
      if $backend is "$crawlable_source"; then
         crawl_with $backend "$json"
         return $?
      fi
   done
   log "unknown backend for $crawlable_source"
   return 1
}

crawl_with() {
   local backend="$1"
   local json="$2"
   log not impl crawl with
   return 1
}

is_crawlable() {
   # https://unix.stackexchange.com/questions/181254/how-to-use-grep-and-cut-in-script-to-obtain-website-urls-from-an-html-file
   local url_pattern="(http|https)://[a-zA-Z0-9./?=_%:-]*"
   if echo "$*" | tr -d '\n' | grep -E "^[ ]*$url_pattern[ ]*$"; then
      return 0
   fi
   if echo "$*" | head -n 1 | grep -E "^[ ]*_source_: $url_pattern[ ]*$"; then
      return 0
   fi
   return 1
}

rewrite() {
   log not impl rewrite
   return 1
}

notea() (
   ncurl() {
      curl -sS "$@"
   }

   ids() {
      ncurl $NOTEA_ADDR/api/tree \
         | jq -r '.items \
         | to_entries[].value.id' \
         | grep -v '^root$'
   }

   get() {
      local cache_key="notea cache $1"
      if cache get "$cache_key"; then
         return 0
      fi
      _get "$@" | cache put "$cache_key"
   }

   _get() {
      ncurl $NOTEA_ADDR/api/notes/$1
   }

   "$@"
)

cache() (
   path() {
      echo "$CACHE/$(echo "$*" | base64)"
   }
   get() {
      local path="$(path "$*")"
      if ! [ -f "$path" ]; then
         return 1
      fi
      if wc -c "$path" | grep -q '^[ ]*0[ ]*$'; then
         return 1
      fi
      local created="$(date -r "$path" +%s)"
      local now="$(date +%s)"
      if ((now-created > CACHE_DURATION)); then
         return 1
      fi
      cat "$path"
   }
   put() {
      local path="$(path "$*")"
      tee "$path"
   }
   "$@"
)

gitlab() (
   is() {
      echo "$*" | grep -q gitlab.app && ! echo "$*" | grep -q '/wiki/'
   }

   gcurl() {
      local cache_key="gitlab gcurl $*"
      if cache get "$cache_key"; then
         return 0
      fi
      _gcurl "$@" | cache put "$cache_key"
   }

   _gcurl() {
      curl -sS -H "Authorization: Bearer $GITLAB_PAT" "$@"
   }

   expand() {
      local cache_key="gitlab expand $*"
      if cache get "$cache_key"; then
         return 0
      fi
      _expand "$@" | sort | cache put "$cache_key"
   }

   _expand() {
      local url="$1"
      local project="$(url_to_project_root "$url" | head -n 1)"
      local root="$(url_to_project_root "$url" | tail -n 1)"
      __expand "$project" "$root"
   }

   url_to_project_root() {
      local url="$1"
      local url_path="${url#http*://gitlab*.net/}"
      local project="${url_path%%/-/*}"
      local root="${url_path#*/-/}"
      local root="${root#tree/}"
      local root="${root#blob/}"
      local root="${root#*/}"
      echo "$project"
      echo "$root"
   }

   __expand() {
      local project="$1"
      local root="${2:-"/"}"

      local b64_files=()
      local b64_trees=("$root")
      local i=0

      find_each() {
         local type="$1"
         shift
         echo "$*" \
            | jq -c .[] \
            | grep "\"type\":\"$type\"" \
            | jq -r .path \
            | while read -r line; do echo "$line" | base64; done \
            | grep .
      }
      while [ "$i" -lt "${#b64_trees[@]}" ]; do
         got="$(list_tree "$project" "${b64_trees[i]}")"
         for b64_tree in $(find_each "tree" "$got"); do
            if ! echo "${b64_trees[@]}" | grep -q "[ ^]$b64_tree[ $]"; then
               b64_trees+=("$b64_tree")
            fi
         done
         for b64_file in $(find_each "blob" "$got"); do
            if ! echo "${b64_files[@]}" | grep -q "[ ^]$b64_file[ $]"; then
               b64_files+=("$b64_file")
            fi
         done
         i=$((i+1))
      done
      for b64_file in "${b64_files[@]}"; do
         echo "$b64_file" | base64 --decode
      done
   }

   list_tree() {
      local project="$(urlencode "$1")"
      local path="/api/v4/projects/$project/repository/tree"
      local query="recursive=true&path=$2"
      gcurl "https://gitlab-app.eng.qops.net/$path?$query"
   }

   "$@"
)

urlencode() (
    LC_COLLATE=C
    local length="${#1}"
    for (( i = 0; i < length; i++ )); do
        local c="${1:$i:1}"
        case $c in
            [a-zA-Z0-9.~_-]) printf '%s' "$c" ;;
            *) printf '%%%02X' "'$c" ;;
        esac
    done
)

if [ "$0" == "$BASH_SOURCE" ]; then
   main "$@"
fi