require 'cgi'
require "base64"

module CouchRest
  class Database
    attr_reader :server, :host, :name, :root
    attr_accessor :bulk_save_cache_limit
     
    # 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}"
      @streamer = Streamer.new(self)
      @bulk_save_cache = []
      @bulk_save_cache_limit = 50
    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 = {}
      keys = params.delete(:keys)
      url = CouchRest.paramify_url "#{@root}/_all_docs", params
      if keys
        CouchRest.post(url, {:keys => keys})
      else
        CouchRest.get url
      end
    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 slow_view funcs, params = {}
      keys = params.delete(:keys)
      funcs = funcs.merge({:keys => keys}) if keys
      url = CouchRest.paramify_url "#{@root}/_slow_view", params
      JSON.parse(RestClient.post(url, funcs.to_json, {"Content-Type" => 'application/json'}))
    end
    
    # backwards compatibility is a plus
    alias :temp_view :slow_view
  
    # 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 = {}, &block
      keys = params.delete(:keys)
      url = CouchRest.paramify_url "#{@root}/_view/#{name}", params
      if keys
        CouchRest.post(url, {:keys => keys})
      else
        if block_given?
          @streamer.view(name, params, &block)
        else
          CouchRest.get url
        end
      end
    end
    
    # GET a document from CouchDB, by id. Returns a Ruby Hash.
    def get id
      slug = escape_docid(id)
      hash = CouchRest.get("#{@root}/#{slug}")
      doc = if /^_design/ =~ hash["_id"]
        Design.new(hash)
      else
        Document.new(hash)
      end
      doc.database = self
      doc
    end
    
    # GET an attachment directly from CouchDB
    def fetch_attachment docid, name
      slug = escape_docid(docid)        
      name = CGI.escape(name)
      RestClient.get "#{@root}/#{slug}/#{name}"
    end
    
    # PUT an attachment directly to CouchDB
    def put_attachment doc, name, file, options = {}
      docid = escape_docid(doc['_id'])
      name = CGI.escape(name)
      uri = if doc['_rev']
        "#{@root}/#{docid}/#{name}?rev=#{doc['_rev']}"
      else
        "#{@root}/#{docid}/#{name}"
      end
        
      JSON.parse(RestClient.put(uri, file, options))
    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.
    #
    # If <tt>bulk</tt> is true (false by default) the document is cached for bulk-saving later.
    # Bulk saving happens automatically when #bulk_save_cache limit is exceded, or on the next non bulk save.
    def save (doc, bulk = false)
      if doc['_attachments']
        doc['_attachments'] = encode_attachments(doc['_attachments'])
      end
      if bulk
        @bulk_save_cache << doc
        return bulk_save if @bulk_save_cache.length >= @bulk_save_cache_limit
        return {"ok" => true} # Compatibility with Document#save
      elsif !bulk && @bulk_save_cache.length > 0
        bulk_save
      end
      result = if doc['_id']
        slug = escape_docid(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
      if result['ok']
        doc['_id'] = result['id']
        doc['_rev'] = result['rev']
        doc.database = self if doc.respond_to?(:database=)
      end
      result
    end
    
    # POST an array of documents to CouchDB. If any of the documents are
    # missing ids, supply one from the uuid cache.
    #
    # If called with no arguments, bulk saves the cache of documents to be bulk saved.
    def bulk_save (docs = nil)
      if docs.nil?
        docs = @bulk_save_cache
        @bulk_save_cache = []
      end
      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>.
    #
    # If <tt>bulk</tt> is true (false by default) the deletion is recorded for bulk-saving (bulk-deletion :) later.
    # Bulk saving happens automatically when #bulk_save_cache limit is exceded, or on the next non bulk save.
    def delete (doc, bulk = false)
      raise ArgumentError, "_id and _rev required for deleting" unless doc['_id'] && doc['_rev']      
      if bulk
        @bulk_save_cache << { '_id' => doc['_id'], '_rev' => doc['_rev'], '_deleted' => true }
        return bulk_save if @bulk_save_cache.length >= @bulk_save_cache_limit
        return { "ok" => true } # Mimic the non-deferred version
      end
      slug = escape_docid(doc['_id'])        
      CouchRest.delete "#{@root}/#{slug}?rev=#{doc['_rev']}"
    end
    
    # COPY an existing document to a new id. If the destination id currently exists, a rev must be provided.
    # <tt>dest</tt> can take one of two forms if overwriting: "id_to_overwrite?rev=revision" or the actual doc
    # hash with a '_rev' key
    def copy doc, dest
      raise ArgumentError, "_id is required for copying" unless doc['_id']
      slug = escape_docid(doc['_id'])        
      destination = if dest.respond_to?(:has_key?) && dest['_id'] && dest['_rev']
        "#{dest['_id']}?rev=#{dest['_rev']}"
      else
        dest
      end
      CouchRest.copy "#{@root}/#{slug}", destination
    end
    
    # MOVE an existing document to a new id. If the destination id currently exists, a rev must be provided.
    # <tt>dest</tt> can take one of two forms if overwriting: "id_to_overwrite?rev=revision" or the actual doc
    # hash with a '_rev' key
    def move doc, dest
      raise ArgumentError, "_id and _rev are required for moving" unless doc['_id'] && doc['_rev']
      slug = escape_docid(doc['_id'])        
      destination = if dest.respond_to?(:has_key?) && dest['_id'] && dest['_rev']
        "#{dest['_id']}?rev=#{dest['_rev']}"
      else
        dest
      end
      CouchRest.move "#{@root}/#{slug}?rev=#{doc['_rev']}", destination
    end
    
    # Compact the database, removing old document revisions and optimizing space use.
    def compact!
      CouchRest.post "#{@root}/_compact"
    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 escape_docid id      
      /^_design\/(.*)/ =~ id ? "_design/#{CGI.escape($1)}" : CGI.escape(id) 
    end

    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