package planr

import (
  "github.com/BurntSushi/toml"
)
/*
  TODO: Every property defined within the defaults currently 
  has to implement the "inherit" method to conditionally inherit a
  property in relation to a parent. (Ostensibly so that test cases
  can override default configuration.) This is pedantic because 
  most properties will end up writing boilerplate amounting to:

  parent.inherit()
  ...
  if config.property == nil {
    config.property = config.parent.property
  }

  This library provides copying behavior between structs
  with common properties using reflection. It seems like
  a slight abuse of reflection... But, it could be 
  retro-fitted to implement this behavior if a "onlyCopyZeroFields"
  option was provided.

  > "github.com/jinzhu/copier"
*/

// Inheritable configuration can inherit properties defined in a
// defaults file. This happens on a per-directory basis so multiple
// tests can share common configuration.
//
// The parent will always be of the same type as the child and an
// assertion is required to define the proper behavior.
type InheritableConfig interface {
  Inherit(parent interface{})
}


// Program-wide configuration which is recognized
// in defaults.toml
type Defaults struct {
  Description string
  Points      *float32
  Adapter     string

  /*
    The TOML library only parses exported fields.
    The Adapters field is an intermediate mapping
    individual adapters to their locally defined
    configuration. After they individually process
    the configuration, it is mapped to the adapters_
    field.

    See: decodeAdapters()
  */
  Adapters    *map[string] toml.Primitive
  adapters_    map[string] InheritableConfig

  /*
    The configs_ field is necessary to properly
    implement the Inherit method using a common
    interface. 
  */
  configs_    *[]AdapterConfig
}


// The default configuration must be able in inherit from
// other defaults further up the tree
//
// This provides multiple levels of configurability
func (child *Defaults) Inherit(p interface{}) {
  parent := p.(Defaults)

  // Inherit properties which haven't been configured
  if child.Points == nil {
    child.Points = parent.Points
  }

  if child.Adapter == "" {
    child.Adapter = parent.Adapter
  } 

  if child.Description == "" {
    child.Description = parent.Description
  }

  // Call the inherit method as defined by the adapters
  // If an adapter is undefined, inherit the parent configuration
  //
  // _configs represents all adapters (registered to a runner)
  for _, adapter := range *parent.configs_ {
    parent_adapter, parent_exists := parent.adapters_[adapter.Name]
    child_adapter,  child_exists  := child.adapters_[adapter.Name]

    if parent_exists {
      if child_exists {
        child_adapter.Inherit(parent_adapter)
      } else {
        child.adapters_[adapter.Name] = parent_adapter 
      }
    }
  }
}

// Parses the intermediate adapters Adapters containing TOML primitives 
// according to methods registered with the runner
// Once parsed, they are stored alongside the registered name to determine
// which adapter will receive the configuration
func (defaults *Defaults) decodeAdapters(
  adapters []AdapterConfig,
  asDefault bool,
) error {
  defaults.configs_ = &adapters
  defaults.adapters_ = make(map[string]InheritableConfig)

  if defaults.Adapters != nil {
    for _, config := range adapters {
      primitive, exists := (*defaults.Adapters)[config.Name]
    
      if exists {
        var parsed InheritableConfig
        var err error
        if asDefault {
          parsed, err = config.ParseDefaultConfig(primitive)
        } else {
          parsed, err = config.ParseConfig(primitive)
        }

        if err != nil {
          return err
        }

        defaults.adapters_[config.Name] = parsed
      }
    }
  }

  return nil
}

// Decode defaults.toml
func DecodeRubricDefaults(path string, adapterCfg []AdapterConfig) (Defaults, error) {
  defaults := Defaults { }

  if _, err := toml.DecodeFile(path, &defaults); err != nil {
    return defaults, err
  }

  if err := defaults.decodeAdapters(adapterCfg, true); err != nil {
    return defaults, err
  }


  return defaults, nil
}

// Decode an individual unit
func DecodeRubricConfig(path string, adapterCfg []AdapterConfig) (TestCaseConfig, error) {
  config := TestCaseConfig { }

  if _, err := toml.DecodeFile(path, &config); err != nil {
    return config, nil
  }

  if err := config.decodeAdapters(adapterCfg, false); err != nil {
    return config, err
  }

  return config, nil
}