[DOCS] Adds Kibana docs for Canvas functions (#26467) (#26733)

* [DOCS] Migrates Canvas function docs to Kibana docs

* [DOCS] Add docs for TinyMath Canvas functions

docs/canvas.asciidoc

@@ -16,8 +16,16 @@ you make neat stuff and you want to show that neat stuff to others. Canvas is
 for makers who are a little bit creative, a little bit technical, and whole lot 
 of curious.
 
-We've put together <<canvas-getting-started, this Getting Started>> to teach you 
-how to get the most out of Canvas. 
+[role="screenshot"]
+image::images/canvas_workpad_weblog.png[]
+
+
+We've put together <<canvas-getting-started, this Getting Started>> to get you
+up and running with Canvas. 
+
+If you want to dig into the expression language and the functions that drive 
+Canvas, see the <<canvas-common-functions>> and 
+<<canvas-tinymath-functions>>.
 
 --
 
@@ -25,3 +33,12 @@ include::canvas/canvas-getting-started.asciidoc[]
 
 include::canvas/canvas-workpad.asciidoc[]
 
+include::canvas/canvas-function-reference.asciidoc[]
+
+include::canvas/canvas-common-functions.asciidoc[]
+
+include::canvas/canvas-server-functions.asciidoc[]
+
+include::canvas/canvas-client-functions.asciidoc[]
+
+include::canvas/canvas-tinymath-functions.asciidoc[]

docs/canvas/canvas-client-functions.asciidoc

@@ -0,0 +1,82 @@
+[[canvas-client-functions]]
+=== Canvas client functions
+
+beta[]These functions must execute in a browser. They are only available
+from within the Canvas application, not via the Canvas HTTP API. These functions must 
+execute in the browser because they use browser specific APIs, such as location, 
+or interact with the workpad to read filters.
+
+A *** denotes a required argument.
+
+[float]
+=== asset
+
+Uses Canvas workpad asset objects to provide argument values. Usually images.
+
+*Accepts:* null
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|_Unnamed_*
+|string
+|The ID of the asset value to return
+|===
+
+*Returns:* string
+
+
+[float]
+=== browser
+
+Forces the interpreter to return to the browser.
+
+*Accepts:* Anything or nothing
+
+*Returns:* Depends on your input and arguments
+
+[float]
+=== filters
+
+Collects element filters on the workpad, usually to provide them to a data source.
+
+*Accepts:* null
+
+*Returns:* filter
+
+[float]
+=== location
+
+Uses the browser's location functionality to get your current location. Usually 
+quite slow, but fairly accurate.
+
+*Accepts:* null
+
+*Returns:* datatable
+
+[float]
+=== urlparam
+
+Accesses URL parameters and use them in expressions. This will always return a string.
+
+*Accepts:* null
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|_Unnamed_*  (Aliases: `var`, `variable`)
+|string
+|The URL hash parameter to access
+
+|default
+|string
+|Return this string if the url parameter is not defined  (default: `""`)
+|===
+
+*Returns:* string

docs/canvas/canvas-function-reference.asciidoc

@@ -0,0 +1,16 @@
+[[canvas-function-reference]]
+== Canvas function reference
+
+beta[] Behind the scenes, Canvas is driven by a powerful expression language,
+with dozens of functions and other capabilities, including table transforms, 
+type casting, and sub-expressions.
+
+For the purpose of this documentation, 
+the Canvas functions are divided by the environment they run in:
+
+* <<canvas-common-functions>> can run anywhere
+* <<canvas-server-functions>> can only execute on the server
+* <<canvas-client-functions>> must execute in a browser
+
+The Canvas expression language also supports <<canvas-tinymath-functions>>, which
+perform complex math calculations.

docs/canvas/canvas-server-functions.asciidoc

@@ -0,0 +1,210 @@
+[[canvas-server-functions]]
+=== Canvas server functions
+
+beta[]These functions can only execute on the server. This may be for performance
+or security reasons, or because the function uses an API only available on the 
+{kib} server. If the expression is executing in the browser, it will transfer to 
+the server when it hits one of these functions.
+
+A *** denotes a required argument.
+
+[float]
+=== demodata
+
+A mock data set that includes project CI times with usernames, countries, and run phases.
+
+*Accepts:* filter
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|_Unnamed_ (Alias: `type`)
+|string
+|The name of the demo data set to use  (default: `ci`)
+|===
+
+*Returns:* datatable
+
+
+[float]
+=== esdocs
+
+Queries {es} and gets back raw documents. Specify the fields you want to receive, 
+especially if you are asking for a lot of rows.
+
+*Accepts:* filter
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|index
+|string
+|Specify an index pattern, for example, "logstash-*"  (default is `_all`)
+
+|_Unnamed_ (Aliases: `query`, `q`)
+|string
+|A Lucene query string (default: `_index:.kibana`)
+
+|sort
+|string
+|Sort directions as "field, direction", for example, "@timestamp, desc" or "bytes, asc"
+
+|fields
+|string
+|Comma separated list of fields. Fewer fields will perform better
+
+|metaFields
+|string
+|Comma separated list of meta fields, for example, "_index,_type"
+
+|count
+|number
+|The number of docs to pull back. Smaller numbers perform better (default: `100`)
+|===
+
+*Returns:* datatable
+
+
+[float]
+=== escount
+
+Queries {es} for a count of the number of hits matching a query.
+
+*Accepts:* filter
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|index
+|string
+|Specify an index pattern, for example, "logstash-*"  (default: `all`)
+
+|_Unnamed_  (Alias: `query`, `q`)
+|string
+|A Lucene query string (default: `"-_index:.kibana"`)
+|===
+
+*Returns:* number
+
+
+[float]
+=== essql
+
+Specifies an {es} SQL.
+
+*Accepts:* filter
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|_Unnamed_*  (Alias: `query`, `q`)
+|string
+|An SQL query
+
+|count
+|number
+|The default is `1000`
+|===
+
+*Returns:* datatable
+
+
+[float]
+=== pointseries
+
+Turns a datatable into a point series model. Currently Canvas differentiates measure 
+from dimensions by looking for a <<canvas-tinymath-functions, Tiny Math function>>. If you enter a TinyMath 
+expression in your argument, Canvas treats that argument as a measure. Otherwise, it 
+is a dimension. Dimensions are combined to create unique keys. Measures are 
+then deduplicated by those keys using the specified TinyMath function.
+
+*Accepts:* datatable
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|x
+|string
+|The values along the X-axis
+
+|y
+|string
+|The values along the Y-axis
+
+|color
+|string
+|An expression to use in determining the mark's color
+
+|size
+|string
+|For elements that support it, the size of the marks
+
+|text
+|string
+|For use in charts that support it, the text to show in the mark
+|===
+
+*Returns:* pointseries
+
+
+[float]
+=== server
+
+Forces the interpreter to return to the server.
+
+*Accepts:* Anything or nothing
+
+*Returns:* Depends on your input and arguments
+&nbsp;
+
+[float]
+=== timelion
+
+Uses Timelion to extract one or more time series from many sources.
+
+*Accepts:* filter
+
+[cols="3*^<"]
+|===
+s|Argument
+s|Type
+s|Description
+
+|_Unnamed_ (Aliases: `query`, `q`)
+|string
+|A Timelion query (default: `".es(*)"`)
+
+|interval
+|string
+|Bucket interval for the time series (default: `auto`)
+
+|from
+|any
+|{es} date math string for the start of the time range (default: `now-1y`)
+
+|to
+|any
+|{es} date math string for the end of the time range (default: `now`)
+
+|timezone
+|any
+|Time zone for the time range (default: `UTC`)
+|===
+
+*Returns:* datatable
+

docs/canvas/canvas-workpad.asciidoc

@@ -1,5 +1,5 @@
 [[canvas-workpad]]
-== Using the workpad
+=== Using the workpad
 
 beta[]Now that you have a workpad with sample data that you can mess with, let’s mess with it. 
 We’ll start out by making a few stylistic changes.