require 'cgi'
require "base64"

module CouchRest
  class Database
    attr_reader :server, :host, :name, :root
     
    # Create a CouchRest::Database adapter for the supplied CouchRest::Server and database name.
    # 
    # ==== Parameters
    # server<CouchRest::Server>:: database host
    # name<String>:: database name
    #
    def initialize server, name
      @name = name
      @server = server
      @host = server.uri
      @root = "#{host}/#{name}"
    end
    
    # returns the database's uri
    def to_s
      @root
    end
    
    # GET the database info from CouchDB
    def info
      CouchRest.get @root
    end
    
    # Query the <tt>_all_docs</tt> view. Accepts all the same arguments as view.
    def documents params = nil
      url = CouchRest.paramify_url "#{@root}/_all_docs", params
      CouchRest.get url  
    end
  
    # POST a temporary view function to CouchDB for querying. This is not recommended, as you don't get any performance benefit from CouchDB's materialized views. Can be quite slow on large databases.
    def temp_view funcs, params = nil
      url = CouchRest.paramify_url "#{@root}/_temp_view", params
      JSON.parse(RestClient.post(url, funcs.to_json, {"Content-Type" => 'application/json'}))
    end
  
    # Query a CouchDB view as defined by a <tt>_design</tt> document. Accepts paramaters as described in http://wiki.apache.org/couchdb/HttpViewApi
    def view name, params = nil
      url = CouchRest.paramify_url "#{@root}/_view/#{name}", params
      CouchRest.get url
    end
    
    # GET a document from CouchDB, by id. Returns a Ruby Hash.
    def get id
      slug = CGI.escape(id) 
      CouchRest.get "#{@root}/#{slug}"
    end
    
    # GET an attachment directly from CouchDB
    def fetch_attachment doc, name
      doc = CGI.escape(doc)
      name = CGI.escape(name)
      RestClient.get "#{@root}/#{doc}/#{name}"
    end
    
    # Save a document to CouchDB. This will use the <tt>_id</tt> field from the document as the id for PUT, or request a new UUID from CouchDB, if no <tt>_id</tt> is present on the document. IDs are attached to documents on the client side because POST has the curious property of being automatically retried by proxies in the event of network segmentation and lost responses.
    def save doc
      if doc['_attachments']
        doc['_attachments'] = encode_attachments(doc['_attachments'])
      end
      if doc['_id']
        slug = CGI.escape(doc['_id'])
        CouchRest.put "#{@root}/#{slug}", doc
      else
        begin
          slug = doc['_id'] = @server.next_uuid
          CouchRest.put "#{@root}/#{slug}", doc
        rescue #old version of couchdb
          CouchRest.post @root, doc
        end
      end
    end
    
    # POST an array of documents to CouchDB. If any of the documents are missing ids, supply one from the uuid cache.
    def bulk_save docs
      ids, noids = docs.partition{|d|d['_id']}
      uuid_count = [noids.length, @server.uuid_batch_count].max
      noids.each do |doc|
        nextid = @server.next_uuid(uuid_count) rescue nil
        doc['_id'] = nextid if nextid
      end
      CouchRest.post "#{@root}/_bulk_docs", {:docs => docs}
    end
    
    # DELETE the document from CouchDB that has the given <tt>_id</tt> and <tt>_rev</tt>.
    def delete doc
      slug = CGI.escape(doc['_id'])
      CouchRest.delete "#{@root}/#{slug}?rev=#{doc['_rev']}"
    end
    
    # DELETE the database itself. This is not undoable and could be rather catastrophic. Use with care!
    def delete!
      CouchRest.delete @root
    end

    private

    def encode_attachments attachments
      attachments.each do |k,v|
        next if v['stub']
        v['data'] = base64(v['data'])
      end
      attachments
    end

    def base64 data
      Base64.encode64(data).gsub(/\s/,'')
    end
  end
end