sourceafIoc::MappedConfig.fan

** Passed into module contribution methods to allow the method to, err, contribute!
**
** A service can *collect* contributions in three different ways:
** - As an unordered list of values
** - As an ordered list of values
** - As a map of keys and values
** 
** The service defines the *type* of contribution by declaring a parameterised list or map in its 
** ctor or builder method. Contributions must be compatible with the type.
class MappedConfig {
    
    internal const  Type                contribType
    private  const  ServiceDef          serviceDef
    private         InjectionCtx        ctx
    private         Obj:Obj             config
    private         Obj:MappedOverride  overrides 
    
    internal new make(InjectionCtx ctx, ServiceDef serviceDef, Type contribType) {
        if (contribType.name != "Map")
            throw WtfErr("Ordered Contrib Type is NOT map???")
        if (contribType.isGeneric)
            throw IocErr(IocMessages.mappedConfigTypeIsGeneric(contribType, serviceDef.serviceId)) 
        
        this.ctx            = ctx
        this.serviceDef     = serviceDef
        this.contribType    = contribType
        this.config         = Utils.makeMap(keyType, valType)
        this.overrides      = Utils.makeMap(keyType, MappedOverride#)
    }

    ** A util method to instantiate an object, injecting any dependencies. See `Registry.autobuild`.  
    Obj autobuild(Type type) {
        ctx.objLocator.trackAutobuild(ctx, type)
    }
    
    ** Adds a keyed object to the service's configuration.
    Void addMapped(Obj key, Obj val) {
        key = validateKey(key)
        val = validateVal(val)

        if (config.containsKey(key))
            throw IocErr(IocMessages.configMappedKeyAlreadyDefined(key.toStr))

        config[key] = val
    }
    
    ** Adds all the mapped objects to a service's configuration.
    Void addMappedAll(Obj:Obj objects) {
        objects.each |val, key| {
            addMapped(key, val)
        }
    }
    
    ** Overrides an existing contribution by its key. The key must exist.
    ** 
    ** @since 1.2
    Void addOverride(Obj existingKey, Obj overrideKey, Obj overrideVal) {
        overrideKey = validateKey(overrideKey)
        existingKey = validateKey(existingKey)
        overrideVal = validateVal(overrideVal)

        if (overrides.containsKey(existingKey))
            throw IocErr(IocMessages.configOverrideKeyAlreadyDefined(existingKey.toStr, overrides[existingKey].key.toStr))

        if (config.containsKey(overrideKey))
            throw IocErr(IocMessages.configOverrideKeyAlreadyExists(overrideKey.toStr))

        if (overrides.vals.map { it.key }.contains(overrideKey))
            throw IocErr(IocMessages.configOverrideKeyAlreadyExists(overrideKey.toStr))

        overrides[existingKey] = MappedOverride(overrideKey, overrideVal)
    }

    internal Void contribute(InjectionCtx ctx, Contribution contribution) {
        contribution.contributeMapped(ctx, this)
    }

    internal Map getConfig() {
        keys := Utils.makeMap(keyType, keyType)
        config.each |val, key| { keys[key] = key }
        
        // don't alter the class state so getConfig() may be called more than once
        Obj:Obj config := this.config.dup

        ctx.track("Applying config overrides to '$serviceDef.serviceId'") |->| {
            // normalise keys -> map all keys to orig key and apply overrides
            Obj:MappedOverride norm := overrides.dup
            found := true
            while (!norm.isEmpty && found) {
                found = false
                norm = norm.exclude |val, existingKey| {
                    overrideKey := val.key
                    if (keys.containsKey(existingKey)) {
                        keys[overrideKey] = keys[existingKey]
                        found = true
                        
                        ctx.log("'${overrideKey}' overrides '${existingKey}'")
                        config[keys[existingKey]] = val.val
                        return true
                    } else {
                        return false
                    }
                }
            }

            if (!norm.isEmpty) {
                overrideKeys := norm.vals.map { it.key.toStr }.join(", ")
                existingKeys := norm.keys.map { it.toStr }.join(", ")
                throw IocErr(IocMessages.contribOverrideDoesNotExist(existingKeys, overrideKeys))
            }
        }

        return config
    }

    Obj validateKey(Obj key) {
        if (!key.typeof.fits(keyType))
            throw IocErr(IocMessages.mappedConfigTypeMismatch("key", key.typeof, keyType))
        return key
    }

    Obj validateVal(Obj val) {
        if (!val.typeof.fits(valType)) {
            // special case for empty lists - as Obj[,] does not fit Str[,], we make a new Str[,] 
            if (val.typeof.name == "List" && valType.name == "List" && (val as List).isEmpty)
                val = valType.params["V"].emptyList
            else
                throw IocErr(IocMessages.mappedConfigTypeMismatch("value", val.typeof, valType))
        }
        return val
    }

    private once Type keyType() {
        contribType.params["K"]
    }

    private once Type valType() {
        contribType.params["V"]
    }

    override Str toStr() {
        "MappedConfig of $contribType"
    }   
}

internal class MappedOverride {
    Obj key; Obj val
    new make(Obj key, Obj val) {
        this.key = key
        this.val = val
    }
    override Str toStr() {
        "[$key:$val]"
    }
}