Bargain is UI-based exchange system used by Goddess Statues and Horned Statue. Most parts of the bargain system can be controlled by datapacks, not just adjusting individual recipes but creating entirely new set of catalog, separate from Paraglider's content.

Each bargain recipe adds one entry to the set bargain catalog. Bargain recipes have list of demands and offers, which can be an item, Heart Container, Stamina Vessel, or Essence (player bound pseudo-currency used by Horned Statue).

{
  "type": "paraglider:statue_bargain",

  "bargainType": "paraglider:horned_statue", // valid bargain type ID

  "demands": { // optional
    // 0 or more
    "items": [ // optional
      {
        "ingredient": { // ingredient
          "tag": "c:gems/emerald"
        },
        "quantity": 6
      }
    ],
    "heartContainers": 1, // optional
    "staminaVessels": 1, // optional
    "essences": 1 // optional
  },

  "offers": { // optional
    // 0 or more
    "items": [ // optional
      {
        "item": { // item stack
          "id": "minecraft:emerald"
        },
        "quantity": 5
      }
    ],
    "heartContainers": 1, // optional
    "staminaVessels": 1, // optional
    "essences": 1 // optional
  }
}

{
  "type": "paraglider:statue_bargain",

  "bargainType": "paraglider:horned_statue", // valid bargain type ID

  "demands": { // optional
    // 0 or more
    "items": [ // optional
      {
        "ingredient": { // ingredient
          "item": "minecraft:emerald"
        },
        "quantity": 6 // optional, default: 1
      }
    ],
    "heartContainers": 1, // optional
    "staminaVessels": 1, // optional
    "essences": 1 // optional
  },

  "offers": { // optional
    // 0 or more
    "items": [ // optional
      {
        "count": 5,
        "item": "minecraft:emerald" // item ID
      }
    ],
    "heartContainers": 1, // optional
    "staminaVessels": 1, // optional
    "essences": 1 // optional
  }
}

A bargain type denotes a unique type of bargain recipe catalog. When the bargain UI is opened, the game uses ID of the bargain type to choose the right recipes for the catalog.

Adding a new bargain type needs a JSON file at location [datapack namespace]/paraglider/bargain_types/[bargain type name].json. The corresponding ID of the bargain type will be [datapack namespace]:[bargain type name]. Subdirectories are also valid location.

• For example, JSON file of default bargain type paraglider:goddess_statue is located at paraglider/paraglider/bargain_types/goddess_statue.json.

{
  "dialog": {
    "initial": [ {/*...*/} ], // bargain dialog, 0 or more
    "success": [ {/*...*/} ], // bargain dialog, 0 or more
    "fail": [ {/*...*/} ], // bargain dialog, 0 or more

    "initial_fallback": {/*...*/}, // bargain dialog, optional
    "success_fallback": {/*...*/}, // bargain dialog, optional
    "fail_fallback": {/*...*/}, // bargain dialog, optional
  }
}

Bargain type also contains dialog information for the UI. The dialogs are divided into three categories, each corresponding to three contexts dialog is displayed:

• Initial (on UI open) dialog,
• on-success dialog,
• and on-fail dialog.

A single dialog have four components:

• Text component,
• random weight,
• set of "bargain recipe tags,"
• and set of "bargain failure reasons."

Each time a bargain dialog is displayed, one dialog entry is chosen randomly from the list. For on-success context, only entries that matches the bargain recipe tags will be included. For on-fail context, bargain failure reasons will be checked in addition to tags.

If no dialog matches the condition, fallback dialog is displayed, if exists. Fallback dialog ignores conditional checks.

Bargain recipe has a set of strings that describe the property of the recipe for dialogs. This system is not related to registry tags.

Recipe tags are checked in on-success and on-fail dialog context. Dialog will only get displayed if all tags specified in the dialog are included in the recipe's tags.

Below is a list of tags used in bargain recipe.

Also note that, for custom bargain recipes, it is possible for other strings to be used as tags.

Bargain failure reasons are checked in on-fail dialog context. After the user tries to bargain and fails, the UI will try to display a dialog that is relevant for the interaction.

Bargain failure reasons describe "reasons" behind missing criteria for successful bargain, such as missing item or Heart Container. Dialog will only get displayed if all reasons specified in the dialog are included in the set of failure reasons.

Below is a list of tags returned by bargain recipe.

Also note that, for custom bargain recipes, it is possible for other strings to be used as reasons.

Let's look into how dialog selection works with an example.

{ // bargain type
  "dialog": {
    "fail": [
      {
        "dialog": { "text": "A" }
      },
      {
        "dialog": { "text": "B" },
        "reason": [ "not_enough_items" ]
      },
      {
        "dialog": { "text": "C" },
        "reason": [ "not_enough_hearts" ]
      },
      {
        "dialog": { "text": "D" },
        "reason": [ "not_enough_items", "not_enough_hearts" ]
      }
    ],

    "fail_fallback": {
      "dialog": { "text": "E" }
    }
  }
}

{ // bargain recipe
  "demands": {
    "items": [
      {
        "ingredient": { "item": "minecraft:diamond" },
        "quantity": 1
      }
    ],
    "heartContainers": 1,
    "staminaVessels": 1
  },

  "offers": {
    // ...
  }
}

If a player has no Heart Containers and no diamonds:

• Dialog A can be displayed, since it has no conditions.
• Dialog B can be displayed, since the failure reason has not_enough_items.
• Dialog C can be displayed, since the failure reason has not_enough_hearts.
• Dialog D can be displayed, since the failure reason has both not_enough_items and not_enough_hearts.
• Dialog E can't be displayed, since at least one non-fallback dialog is valid.

If a player has no Heart Containers, but a diamond:

• Dialog A can be displayed, since it has no conditions.
• Dialog B can't be displayed, since the failure reason doesn't have not_enough_items.
• Dialog C can be displayed, since the failure reason has not_enough_hearts.
• Dialog D can't be displayed, since the failure reason has not_enough_hearts but not not_enough_items.
• Dialog E can't be displayed, since at least one non-fallback dialog is valid.

If a player has a Heart Container and a diamond, but no Stamina Vessels:

• Dialog A can be displayed, since it has no conditions.
• Dialog B can't be displayed, since the failure reason doesn't have not_enough_items.
• Dialog C can't be displayed, since the failure reason doesn't have not_enough_hearts.
• Dialog D can't be displayed, since the failure reason doesn't have not_enough_items nor not_enough_hearts.
• Dialog E can't be displayed, since at least one non-fallback dialog is valid.

{
  "dialog": { // text component
    "translate": "bargain.dialog.goddess_statue.failure.not_enough_items.0"
  },
  "weight": 1, // optional, default: 1
  "tag": [ // bargain recipe tags, optional
    "gives_heart_container"
  ],
  "reason": [ // bargain failure reasons, optional
    "not_enough_items"
  ]
}