id: json_config
label: JSON Config
flags: [ show_id, python ]

parameters:
-   id: config_file
    label: Config File
    dtype: file_open
    default: ""
-   id: schema_file
    label: Config Schema
    dtype: file_open
    default: ""
# Not my favorite thing because it doesn't explicitly close the file, but
# it should be okay.  The garbage collector will take care of it.
value: "${ json.load(open(config_file)) }"

asserts:
- ${ schema_file == "" or validate(json.load(open(config_file)), json.load(open(schema_file))) is None }

templates:
    imports: |-
        import json
        from jsonschema import validate
    # Note that yaml makes it really hard to insert spaces at the beginning of the line.
    # The "\" char below is used to escape the space at the beginning of a line.
    var_make: "with open(${config_file}) as fid:\n\
              \    self.${id} = ${id} = json.load(fid)\n\
              self.${id}_schema = ${id}_schema = ${schema_file}\n\
              if ${id}_schema:\n\
              \    with open(${id}_schema) as fid:\n\
              \        validate(${id}, json.load(fid))"

documentation: |-
    This block represents a json config file that is read in as a dictionary.

    The values can be used directly when instantiating blocks.  For example,
    Sample Rate: yaml_config["samp_rate"]

    Optionally, a json schema can be specified to validate the configuration.

    For example, you could have a json file that contains:
    {
      "samp_rate": 1e6,
    }
    And a schema that contains
    {
      "type": "object",
      "properties": {
        "samp_rate": {"type": "number", "exclusiveMinimum": 0}
       }
    }

    If the id of this block is json_config_0, then you can access the samp rate
    in other blocks as json_config_0["samp_rate"]


file_format: 1