#!/bin/bash

# If this file has already been sourced, just return
test $(ENVIRONMENT_SH+isset) && return
declare -g ENVIRONMENT_SH=true

#
# Environtments are stored as a list of lists
# Each list is a "call stack", and popped from the list of lists when the current scope is exited
# Each list is of the form 
#    (name-1 variable-token-1 ... name-N variable-token-N)
# Where:
#    name is the name of the variable in the environment
#    variable-key is the token to lookup a value using the variable:: api
#

source ${BASH_SOURCE%/*}/common.sh
source ${BASH_SOURCE%/*}/variables.sh
source ${BASH_SOURCE%/*}/variables.arraylist.sh
source ${BASH_SOURCE%/*}/variables.linkedlist.sh
source ${BASH_SOURCE%/*}/variables.stack.sh
source ${BASH_SOURCE%/*}/variables.queue.sh
source ${BASH_SOURCE%/*}/variables.map.sh


declare -g ENVIRONMENT_DEBUG=0

# TODO: This needs to use a LinkedList implementation for the base list of scopes
#       Each scope, on the other hand, should be a Map

#
# environment::new
#
# Creates a brand new environment
# Generally will only be called once at the setup of the interpreter
#
# Returns: The variable-token for the newly created environment
#
proc environment::new {
    if [[ ${ENVIRONMENT_DEBUG} == 1 ]] { stderr "environment::new $(@)" ; }

    variable::LinkedList::new ; setglobal env = $(RESULT)
    variable::Map::new 
    variable::LinkedList::prepend $(env) $(RESULT)
}

#
# environment::addScope <environment-token>
#
# Adds a new scope to the to the environment
#
# Returns: The same environment variable-token that was passed in
#
proc environment::pushScope {
    if [[ ${ENVIRONMENT_DEBUG} == 1 ]] { stderr "environment::pushScope $(@)" ; }

    declare env="$(1)"

    variable::Map::new
    variable::LinkedList::prepend $(env) $(RESULT)

    setglobal RESULT = $(RESULT)
}

#
# environment::popScope <environment-token>
#
# Removes the top level environment from the environment list 
# TODO: Need better names to distinguish "a list of environment lists" and
#       "a list of name value-token pairs"
#
# Returns: The same environment variable-token that was passed in
#
proc environment::popScope {
    if [[ ${ENVIRONMENT_DEBUG} == 1 ]] { stderr "environment::popScope $(@)" ; }

    variable::LinkedList::rest $1
    setglobal RESULT = $(RESULT)
}

#
# environment::hasValue <env token> <key token>
#
# Returns 0 if the key in question exists in the environment
#
proc environment::hasValue {
    if [[ ${ENVIRONMENT_DEBUG} == 1 ]] { stderr "environment::getValue $(@)" ; }

    declare env="$(1)"
    declare name="$(2)"
    declare scope

    variable::new String $(name) ; declare keyToken="$(RESULT)"

    declare currentEnv="$(env)"
    while ! variable::LinkedList::isEmpty_c $(currentEnv) {
        variable::LinkedList::first $(currentEnv)
        setglobal scope = $(RESULT)
        if variable::Map::containsKey_c $(scope) $(name)  {
            return 0
        }

        variable::LinkedList::rest $(currentEnv)
        setglobal currentEnv = $RESULT
    }

    return 1
}

#
# environment::getValue <env token> <key token>
#
# Gets the value for a given key in the specified env
# Error if key does not exist
#
proc environment::getValue {
    if [[ ${ENVIRONMENT_DEBUG} == 1 ]] { stderr "environment::getValue $(@)" ; }

    declare env="$(1)"
    declare name="$(2)"
    declare scope

    variable::new String $(name) ; declare keyToken="$(RESULT)"

    declare currentEnv="$(env)"
    while ! variable::LinkedList::isEmpty_c $(currentEnv) {
        variable::LinkedList::first $(currentEnv)
        setglobal scope = $(RESULT)
        if variable::Map::containsKey_c $(scope) $(name)  {
            variable::Map::get $(scope) $(name)
            return
        }

        variable::LinkedList::rest $(currentEnv)
        setglobal currentEnv = $RESULT
    }

    variable::value $name
    stderr "Variable [$(name)=$(RESULT)] not found in current environment"
    exit 1
}

#
# environment::setVariable <environment-token> <name> <value-token>
#
# Sets a name/variable-token pair on the top level of the environment
#
# Returns 0 if the variable already existed (and was changed)
#         1 if the variable is new
#
#
proc environment::setVariable {
    if [[ ${ENVIRONMENT_DEBUG} == 1 ]] { stderr "environment::setVariable $(@)" ; }

    declare env="$(1)"
    declare keyToken="$(2)"
    declare valueToken="$(3)"

    variable::LinkedList::first $(env)
    declare scope="$(RESULT)"
    declare returnValue

    if variable::Map::containsKey_c $(scope) $(keyToken)  {
        setglobal returnValue = '0'
    } else {
        setglobal returnValue = '1'
    }

    variable::Map::put $(scope) $(keyToken) $(valueToken)
    setglobal RESULT = ''""
    return $returnValue
}


#
# environment::setVariable <environment-token> <name> <value-token>
#
# Sets a name/variable-token pair whereever it is found in the environment list
# or, if the name in question is not found, adds it to the top level
#
proc environment::setOrReplaceVariable {
    if [[ ${ENVIRONMENT_DEBUG} == 1 ]] { stderr "environment::setOrReplaceVariable $(@)" ; }

    declare env="$(1)"
    declare keyToken="$(2)"
    declare valueToken="$(3)"
    declare scope

    declare currentEnv="$(env)"
    while ! variable::LinkedList::isEmpty_c $(currentEnv) {
        variable::LinkedList::first $(currentEnv)
        setglobal scope = $(RESULT)
        if variable::Map::containsKey_c $(scope) $(keyToken)  {
            variable::Map::put $(scope) $(keyToken) $(valueToken)
            setglobal RESULT = ''""
            return 0
        }

        variable::LinkedList::rest $(currentEnv)
        setglobal currentEnv = $RESULT
    }

    # Wasn't found, add it to the first scope in the env
    variable::LinkedList::first $(env)
    setglobal scope = $(RESULT)
    variable::Map::put $(scope) $(keyToken) $(valueToken)
    setglobal RESULT = ''""
    return 1
}

proc environment::print {
    declare currentEnv="$(1)"

    echo "Environment [$(currentEnv)]"

    while ! variable::LinkedList::isEmpty_c $(currentEnv) {
        variable::LinkedList::first $(currentEnv)
        variable::Map::print $(RESULT)

        variable::LinkedList::rest $(currentEnv)
        setglobal currentEnv = $RESULT
    }
}

# ======================================================
if test $0 != $BASH_SOURCE {
    return
}

variable::new String "key one" ; setglobal key1 = $(RESULT)
variable::new String "value one" ; setglobal value1 = $(RESULT)
variable::new String "key two" ; setglobal key2 = $(RESULT)
variable::new String "value two" ; setglobal value2 = $(RESULT)
variable::new String "key three" ; setglobal key3 = $(RESULT)
variable::new String "value three" ; setglobal value3 = $(RESULT)
variable::new String "no such key" ; setglobal keyUnknown = $(RESULT)
declare env1
declare env2
declare env3

environment::new ; setglobal env1 = $(RESULT)

environment::setVariable $(env1) $key1 $value1

# Check that we can get the value out
environment::getValue $(env1) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value one" $(RESULT) "Single variable"

environment::setVariable $(env1) $key2 $value2

# Check that we can get the previously existing key:value out
environment::getValue $(env1) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value one" $(RESULT) "Multiple variables, first"
# And that we can get the new value out
environment::getValue $(env1) $key2 ; \
    variable::value $(RESULT) ; \
    assert::equals "value two" $(RESULT) "Multiple variables, second"

#
# Multiple scope tests / set
#
environment::new ; setglobal env1 = $(RESULT)
environment::setVariable $(env1) $key1 $value1
environment::pushScope $(env1) ; setglobal env2 = $(RESULT)
environment::setVariable $(env2) $key2 $value2

# Make sure we can get the new value out
environment::getValue $(env2) $key2 ; \
    variable::value $(RESULT) ; \
    assert::equals "value two" $(RESULT) "Second scope"
# And a variable from the original scope
environment::getValue $(env2) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value one" $(RESULT) "Variable from first scope"
# Pop off the second scope
environment::popScope $(env2) ; setglobal env3 = $(RESULT)
# and make sure a variable from the first scope is still there
environment::getValue $(env3) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value one" $(RESULT) "Variable from first scope post pop"
# and the variable from the second scope is not
environment::hasValue $(env3) $key2 ; \
    assert::equals 1 $Status "Variable from second scope after we popped it"

#
# Multiple scope tests / setOrReplace
#
environment::new ; setglobal env1 = $(RESULT)
environment::setOrReplaceVariable $(env1) $key1 $value1
environment::pushScope $(env1) ; setglobal env2 = $(RESULT)
environment::setOrReplaceVariable $(env2) $key2 $value2
environment::setOrReplaceVariable $(env2) $key1 $value3

# Make sure we can get the new value out
environment::getValue $(env2) $key2 ; \
    variable::value $(RESULT) ; \
    assert::equals "value two" $(RESULT) "Second scope"
# And a variable from the original scope
environment::getValue $(env2) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value three" $(RESULT) "Variable from first scope"
# Pop off the second scope
environment::popScope $(env2) ; setglobal env3 = $(RESULT)
# and make sure a variable from the first scope is still there (new value)
environment::getValue $(env3) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value three" $(RESULT) "Variable from first scope post pop"
# and the variable from the second scope is not
environment::hasValue $(env3) $key2 ; \
    assert::equals 1 $Status "Variable from second scope after we popped it"



#
# Second scope, [set] value of variable, then make sure the original env has the old value
#
environment::new ; setglobal env1 = $RESULT
environment::setVariable $env1 $key1 $value1
environment::pushScope $(env1) ; setglobal env2 = $RESULT
environment::setVariable $(env2) $key1 $value2

environment::getValue $(env1) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value one" $(RESULT) "setVariable, original env"
environment::getValue $(env2) $key1 ; \
    variable::value $(RESULT) ; \
    assert::equals "value two" $(RESULT) "setVariable, new env"

#
#
#

assert::report

if test $(1+isset) && test $1 == "debug" { 
    variable::printMetadata
}