# Copyright Rene Rivera 2015
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE.txt or copy at
# https://www.bfgroup.xyz/b2/LICENSE.txt)

import args ;
import path ;
import project ;
import modules ;
import regex ;
import type ;

# Add a location, i.e. directory, where to search for libraries.
# The optional 'prefix' indicates which rooted-prefixes the new
# search dir applies to. The prefix defaults to '/'.
rule add-location ( dir prefix ? : base-dir ? )
{
    process-args ;

    prefix ?= "/" ;

    # Dir path of caller to base paths from.
    caller-module ?= [ CALLER_MODULE ] ;
    local caller-dir = [ modules.peek $(caller-module) : __file__ ] ;
    caller-dir = $(caller-dir:D) ;

    base-dir ?= $(caller-dir) ;

    .search-path-prefix += $(prefix) ;
    .search-path.$(prefix) += [ path.root [ path.root $(dir) $(base-dir) ] [ path.pwd ] ] ;
}

# Declares additional definitions of a modular library target external
# to the modular library build itself. This makes it possible to externally
# define modular libraries without modifying the library. The passed in
# values are added on demand when the named library is first declared.
rule external (
    name : sources * : requirements * : default-build * :
    usage-requirements * )
{
    .external.($(name)).sources = $(sources) ;
    .external.($(name)).requirements = $(requirements) ;
    .external.($(name)).default-build = $(default-build) ;
    .external.($(name)).usage-requirements = $(usage-requirements) ;
}

# Find, and declare, any modular libraries referenced in the target-refs.
# This will both load the modular libraries, and declare/manufacture
# the modular libraries as needed.
rule find ( target-refs + )
{
    process-args ;

    local caller-mod = [ CALLER_MODULE ] ;
    local caller-dir = [ modules.peek $(caller-mod) : __file__ ] ;
    caller-dir = $(caller-dir:D) ;
    caller-dir = [ path.root $(caller-dir) [ path.pwd ] ] ;

    local result-refs ;
    for local target-ref in $(target-refs)
    {
        result-refs += [ resolve-reference $(target-ref)
            : $(caller-mod) $(caller-dir) ] ;
    }

    return $(result-refs) ;
}

##############################################################################

local rule resolve-reference ( target-ref : caller-mod caller-dir ? )
{
    # ECHO %%% modular.resolve-target-ref $(target-ref) :: $(caller-mod) $(caller-dir) ;
    if ! $(caller-dir)
    {
        caller-dir = [ modules.peek $(caller-mod) : __file__ ] ;
        caller-dir = $(caller-dir:D) ;
        caller-dir = [ path.root $(caller-dir) [ path.pwd ] ] ;
    }
    local result-ref = $(target-ref) ;
    local ref = [ MATCH ^(.*)//.* : $(target-ref:G=) ] ;
    # if ! ( $(ref) in $(.target-refs) )
    {
        # .target-refs += $(ref) ;
        local search-prefix ;
        local search-sub ;
        for local prefix in $(.search-path-prefix)
        {
            if ! $(search-prefix)
            {
                local search-match = [ MATCH ^($(prefix))/(.*)$ : $(ref) ] ;
                search-prefix = $(search-match[1]) ;
                search-sub = $(search-match[2]) ;
            }
        }

        if $(search-prefix)
        {
            local found = [ path.glob $(.search-path.$(search-prefix)) : $(search-sub) ] ;
            found = $(found[1]) ;
            if $(found)
            {
                local lib-ref = [ regex.split $(search-sub) / ] ;
                lib-ref = $(search-prefix)/$(lib-ref[1]) ;
                local lib-path = [ path.relative-to $(caller-dir) $(found) ] ;
                define-library $(lib-ref) $(caller-mod) : $(lib-path) ;
            }
        }
    }
    return $(result-ref) ;
}

local rule define-library ( name caller-module ? : root )
{
    # ECHO ~~~ modular.library $(name) $(caller-module) :: $(root) :: $(depends) ;

    process-args ;

    # Dir path of caller to base paths from.
    caller-module ?= [ CALLER_MODULE ] ;
    local caller-dir = [ modules.peek $(caller-module) : __file__ ] ;
    caller-dir = $(caller-dir:D) ;

    # Find the various parts of the library.
    local lib-dir = [ path.root [ path.root $(root) $(caller-dir) ] [ path.pwd ] ] ;
    local lib-contents = [ path.glob $(lib-dir) : "include" "build" ] ;
    lib-contents = $(lib-contents:D=) ;

    # "include" dir for library..
    local include-dir ;
    if "include" in $(lib-contents)
    {
        include-dir = $(root)/include ;
    }

    # If it has a build dir, i.e. it has targets to build,
    # we root the project at the build dir to make it easy
    # to refer to the build targets. This mirrors the regular
    # Boost organization of the project aliases.
    if "build" in $(lib-contents)
    {
        root = $(root)/build ;
        build-dir = "." ;
    }

    # Shadow target declarations so that we can alter build targets
    # to work in the standalone modular structure.
    local lib-location = [ path.root [ path.make $(root) ] $(caller-dir) ] ;
    local lib-module-name = [ project.module-name $(lib-location) ] ;
    local modular-rules = [ RULENAMES modular-rules ] ;
    IMPORT modular-rules : $(modular-rules) : $(lib-module-name) : $(modular-rules) ;

    # Load/create/declare library project.
    local lib-module = [ project.find $(root) : $(caller-dir) ] ;
    if ! $(lib-module)
    {
        # If the find was unable to load the project we synthesize it.
        lib-module = [ project.load $(lib-location) : synthesize ] ;
    }
    local lib-target = [ project.target $(lib-module) ] ;
    if ! [ modules.peek $(lib-module) : __library__ ]
    {
        modules.poke $(lib-module) : __library__ : $(name) ;
        for local type in [ modules.peek type : .types ]
        {
            main-rule-name = [ type.type-to-rule-name $(type) ] ;
            IMPORT modular-rules : main-target-rule : $(lib-module-name) : $(main-rule-name) ;
        }
    }

    # Declare project alternate ID.
    modules.call-in $(caller-module) : use-project $(name) : $(root) ;

    # Create a "library" target that has basic usage info if needed.
    if ! [ $(lib-target).has-alternative-for-target library ]
    {
        include-dir = [ path.relative-to $(root) $(include-dir) ] ;

        project.push-current $(lib-target) ;

        # Declare the library alias.
        modules.call-in $(lib-module) : library
            : # Sources
            : # Requirements
            : # Default Build
            : # Usage Requirements
              <include>$(include-dir)
            ;

        project.pop-current ;
    }
}

args.add-arg modular-search-dir : --modular-search-dir
    : "" ;

local rule process-args ( )
{
    if ! $(.did-process-args)
    {
        .did-process-args = yes ;
        local argv = [ modules.peek : ARGV ] ;
        local dirs = [ args.get-arg modular-search-dir ] ;
        for local dir in $(dirs)
        {
            add-location $(dir) : [ path.pwd ] ;
        }
    }
}

rule apply-external (
    mod : field : values * )
{
    local result ;
    local name = [ modules.peek $(mod) : __library__ ] ;
    values += $(.external.($(name)).$(field)) ;
    for local value in $(values)
    {
        result += [ resolve-reference $(value) : $(mod) ] ;
    }
    return $(result) ;
}

module modular-rules
{
    import type ;
    import targets ;
    import builtin ;
    import alias ;

    # Avoids any form of installation for Boost modules.
    rule boost-install ( libraries * ) { }

    # Generic typed target rule to pre-process main target
    # declarations to make them work within the standalone
    # modular structure.
    rule main-target-rule (
        name : sources * : requirements * : default-build * :
        usage-requirements * )
    {
        local mod = [ CALLER_MODULE ] ;

        # ECHO @@@ [[$(mod)]] modular-rules.main-target-rule $(name) :: $(sources) :: $(requirements) :: $(default-build) :: $(usage-requirements) ;

        # First discover the required target type based on the exact alias used to
        # invoke this rule.
        local bt = [ BACKTRACE 1 ] ;
        local rulename = $(bt[4]) ;
        local target-type = [ type.type-from-rule-name $(rulename) ] ;
        return [ targets.create-typed-target $(target-type) : [ project.current ] :
            $(name) : $(sources) : $(requirements) : $(default-build) :
            $(usage-requirements) ] ;
    }

    rule lib ( names + : sources * : requirements * : default-build * :
        usage-requirements * )
    {
        local mod = [ CALLER_MODULE ] ;
        requirements += <use>library ;
        usage-requirements += <use>library ;

        # ECHO @@@ [[$(mod)]] modular-rules.lib $(names) :: $(sources) :: $(requirements) :: $(default-build) :: $(usage-requirements) ;
        return [ builtin.lib $(names) : $(sources) : $(requirements) : $(default-build) : $(usage-requirements) ] ;
    }

    rule alias ( name : sources * : requirements * : default-build * :
        usage-requirements * )
    {
        local mod = [ CALLER_MODULE ] ;

        # ECHO @@@ [[$(mod)]] modular-rules.alias $(name) :: $(sources) :: $(requirements) :: $(default-build) :: $(usage-requirements) ;
        return [ alias.alias $(name) : $(sources) : $(requirements) : $(default-build) : $(usage-requirements) ] ;
    }

    rule library ( name ? : sources * : requirements * : default-build * :
        usage-requirements * )
    {
        import modular ;

        local mod = [ CALLER_MODULE ] ;
        sources = [ modular.apply-external $(mod) : sources : $(sources) ] ;
        requirements = [ modular.apply-external $(mod) : requirements : $(requirements) ] ;
        default-build = [ modular.apply-external $(mod) : default-build : $(default-build) ] ;
        usage-requirements = [ modular.apply-external $(mod) : usage-requirements : $(usage-requirements) ] ;

        name ?= library ;

        # ECHO @@@ [[$(mod)]] modular-rules.library $(name) :: $(sources) :: $(requirements) :: $(default-build) :: $(usage-requirements) ;
        return [ alias.alias $(name) : $(sources) : $(requirements) : $(default-build) : $(usage-requirements) ] ;
    }
}

