# API documentation for `doc_items` (Version 0.3.0)
## Introduction
This document explains the API of `doc_items`. It contains a reference of
all functions.

***Warning***: This mod is still in alpha stage, expect bugs and missing
features!

## Quick start
A common use case for using this API requires only to set some hand-written
help texts for a few items.

To add your description and/or usage help to items, optionally depend on
`doc_items`, use the functions `doc.sub.items.set_items_longdesc` and
`doc.sub.items.set_items_usagehelp` in the following programming idiom:

    if minetest.get_modpath("doc_items") ~= nil then
        doc.sub.items.set_items.longdesc({
            ["example:item1"] = "Long description goes here.",
            ["example:item2"] = "Lour long description goes here.",
        })
        doc.sub.items.set_items.usagehelp({
            ["example:item1"] = "Describe here how this item can be used.",
            ["example:item2"] = "Describe here how this item can be used.",
        })
    end

Don't forget to read at least the documentation of these functions.

If you need more customization, read ahead. ;-)

## Concepts
### Factoids
Basically, a factoid is usually a single sentence telling the player a specific
fact about the item. The task of each factoid is to basically convert parts
of the item definition to useful, readable, understandable text.

Example: It's a fact that `default:sand` has the group `falling_node=1`.
A factoid for this is basically just a simple conditional which puts the
the sentence “This block is affectet to gravity and can fall.” into the
text if the node is member of said group.

Factoids can be more complex than that. The factoid for node drops needs to
account for different drop types and probabilities, etc.

`doc_items` has many predefined factoids already. This includes all “special”
groups (like `falling_node`), drops, mining capabilities, punch interval,
and much more.

Custom factoids can be added with `doc.sub.items.register_factoid`.

The idea behind factoids is to generate as much information as possible
automatically to reduce reduncancy, inconsistencs and the workload of hand-
written descriptions.

### Long description and usage help
Factoids are not always sufficient to describe an item. This is the case
for facts where the item definition can not be used to automatically
generate texts. Examples: Custom formspecs, ABMs, special tool action
on rightclick.

That's where the long description and usage help comes into play.
Those are two texts which are written manually for a specific item.

Roughly, the long description is for describing **what** the item is, how it
acts, what it is for. The usage help is for explaining **how** the
item can be used but it is not needed for standard mining tools and weapons.

For more information, read the recommendations for
`doc.sub.items.set_items_longdesc` and `doc.sub.items.set_items_usagehelp`.

#### Template texts
For your convenience, a few template texts are provided for common texts
to avoid redundancy and to increase consistency for somple things. You can
use these as values in the setter functions. For more complex items, you
should of course write your own texts instead. Read `init.lua` to see the
actual texts.

##### Long description
* `doc.sub.items.temp.build`: For building blocks like the brick block in Minetest Game
* `doc.sub.items.temp.deco`: For other decorational blocks.
* `doc.sub.items.temp.craftitem`: For items solely or almost solely used for crafting

##### Usage help
* `doc.sub.items.temp.eat`: For eatable items using the `on_use=minetest.item_eat(1)` idiom
* `doc.sub.items.temp.eat_bad`: Same as above, but eating them is considered a bad idea

### Forced and suppressed items
By default, an entry for each item is added, except for items in the group
`not_in_creative_inventory`. This default behaviour already covers most
useful items, but it still sometimes needs tweaking.

Entries can be forced, which means they will be forcefully added, against the
default behaviour. Entries can be suppressed which means they will not
be added at all.

The default behaviour can be overridden by two ways: Groups and a funciton call.

Use groups when you can directly define an item (in other words, in **your**
mods).

To force the entry of an items, add the item to the group `in_doc = 1`.
To suppress the entry of an item, add the item to the group `not_in_doc = 1`.

There is also the function `doc.sub.items.add_forced_item_entries` which
forces entries for a number of entries. You should **only** use this function
when you can not use groups.

When there are contradictions, forcing a group takes precedence over suppressing
a group.

#### Example
Think of a node which is supposed to be indestructible. Because such a node is
quite dangerous in Creative Mode, it has been added to the
`not_in_creative_inventory` group. However, documentation of this node is
obviously required, so the entry for this node needs to be **forced**.

## Functions
This is the reference of all available functions in this API.

### `doc.sub.items.set_items_longdesc(longdesc_table)`
Sets the long description of items. `longdesc_table` is
a table where the keys are the itemstrings and the values
are the the description strings for each item.

The long description of an item is a manually written text
to describe a particular item.

#### Default long descriptions
`doc_items` registers two long descriptions by default: For air
and the hand (default tool).
It is possible to overwrite each of them, just call the funcion
as usual.

The hand description is kept very generic, but it might miss
some information on more complex subgames. In this case, the hand's
long description might need overwriting.

#### Recommendations
The long description should roughly contain the following info:

* What the item does
* What it is good for
* How it may be generated in the world
* Maybe some background info if you're in a funny mood
* Notable information which does't fit elsewhere

The desciption should normally **not** contain:

* Information which is already covered by factoids, like digging groups,
  damage, group memberships, etc.
* How the item can be used
* Direct information about other items
* Any other redundant information
* Crafting recipes

One exception from the rule may be for highlighting the most important
purpose of a simple item, like that coal lumps are primarily used as fuel.

Sometimes, a long description is not neccessary because the item is already
exhaustively explained by factoids.

For very simple items, consider using one of the text templates mentioned
above.

Minimal style guide: Use complete sentences.

#### Example
    doc.sub.items.set_items_longdesc({
         ["example:painter"] = "Paints blocks.",
         ["example:flower"] = "Likes to grow on grass when it is near water.",
    })

### `doc.sub.items.set_items_usagehelp(usagehelp_table)`
Sets the usage help texts of items. The function is completely analog
to `doc.sub.items.set_items_longdesc` and has the same syntax, it
only differs in semantics.

The usage help is supposed to describe how the item can be used.

#### Example
    doc.sub.items.set_items_usagehelp({
         ["example:painter"] = "Punch any block to paint it red.",
    })

#### Recommendations
The usage help should only be set for items which are in some way special
in their usage. Standard tools and weapons should never have an usage help.

The rule of thumb is this: If a new player who already knows the Minetest
basics, but not this item, will not direcly know how to use this item,
then the usage help should be added. If basic Minetest knowledge or
existing factoids are completely sufficient, usage help should not be added.

The recommendations for what not to put into the usage help is the same
as for long descriptions.

### `doc.sub.items.register_factoid(category_id, factoid_type, factoid_generator)`
***Note***: This function not fully implemented. It currently supports only
factoids for nodes.

Add a custom factoid (see above) for the specified category.

* `category_id`: The documentation category fow which the factoid applies:
    * `"nodes"`: Blocks
    * `"tools"`: Tools and weapons (***Not yet supported***)
    * `"craftitems"`: Misc. items (***Not yet supported***)
* `factoid_type`: Rough categorization of the factoid's content. Controls
  where in the text the factoid appears. Possible values:
    * `"groups"`: Factoid appears near groups
    * **(more to come)**
* `factoid_generator`: A function which turns item definition into a string
  (see blow)

#### `factoid_generator(itemstring, def)`
`itemstring` is the itemstring of the item to be documented, and `def` is the
complete item definition table (from Minetest).

This function must return a helpful string which turns a part of the item's
definition into an useful sentence or text. The text can contain newlines,
but it must not end with a newline.

This function must **always** return a string. If you don't want to add any text,
return the empty string.

Style guide: Try to use complete sentences and avoid too many newlines.

#### Example
This factoid will add the sentence “This block will extinguish nearby fire.”
to all blocks which are member of the group `puts_out_fire`.

    doc.sub.items.register_factoid("nodes", "groups", function(itemstring, def)
        if def.groups.puts_out_fire ~= nil then
            return "This block will extinguish nearby fire."
        else
            return ""
        end
    end)

### `doc.sub.items.add_real_group_names(groupnames)`
Use this function so set some more readable group names to show them
in the formspec, since the internal group names are somewhat cryptic
to players.

`groupnames` is a table where the keys are the “internal” group names and
the values are the group names which will be actually shown in the
Documentation System.

***Note***: This function is mostly there to work around a problem in
Minetest as it does not support “real” group names, which means exposing
groups to an interface is not pretty. Therefore, this function may be
deprecated when Minetest supports such a thing.

### `doc.sub.items.add_notable_groups(groupnames)`
Add a list of groups you think are notable enough to be mentioned in the
“This item belongs to the following groups: (…)” factoid.

`groupnames` is a table of group names.

By default, no groups are shown for this factoid which means this factoid
is never displayed.

What is “notable” is subjective, but here's a rule of thumb you may follow:

You should add groups with this function if:

* This group is used for crafting purposes
* This group is somehow important for interaction
* This group appears in `connect_to` definitions of nodes

Do not add groups if:

* The group is only used internally
* The group is unteresting for the player
* A factoid covering this group already exists
* Writing a factoid would be more useful
* The group is a mining or damage group
* Rating is important to gameplay (consider writing a factoid instead)

The intention of this function is to give a short rundown of the groups
which are notable as they are important to gameplay in some way yet don't
deserve a full-blown factoid.

### `doc.sub.items.add_notable_groups(groupnames)`
Declare a number of groups as mining groups, that is, groups which are
primarily used for determining mining times. They will appear in the
“Mining capabilities” factoid.

`groupnames` is a table of group names.

### `doc.sub.items.add_forced_item_entries(itemstrings)`
Adds items which will be forced to be added to the entry list, even if
the item is not in creative inventory.

`itemstrings` is a table of itemstrings of items to force the entries for.

***Note***: The recommended way to force item entries is by adding the item
to the group `in_doc=1` (see above). Only use this function when you can
not use groups.

### `doc.sub.items.add_suppressed_item_entries(itemstrings)`
Adds items which will be forced to **not** be added to the entry list.

`itemstrings` is a table of itemstrings of items to force the entries for.

***Note***: The recommended way to suppress item entries is by adding the
item to the group `not_in_doc=1` (see above). Only use this function when you
can not use groups.

### `doc.sub.items.add_item_name_overrides(itemstrings)`
Overrides the entry names of entries to the provided names. By default,
each entry name equals the item's `description` field.

`itemstrings` is a table in which the keys are itemstrings and the values
are the entry titles you want to use for those items.

#### Preset overrides
The following item name overrides are defined by default:

    { [""] = "Hand", 
      ["air"] = "Air" }

It is possible to override **these** names, just use the function normally.

#### Example
    doc.sub.items.add_item_name_overrides({
        ["air"] = "Air", -- original description: “Air (You hacker you!)”
        ["farming:wheat_8"] = "Wheat Plant", -- Item description was empty
        ["example:node"] = "My Custom Name",
    })