# MIT License
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# Copyright The SCons Foundation
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"""Routines for setting up Fortran, common to all dialects."""

import re
import os.path
from typing import Tuple, List

import SCons.Scanner.Fortran
import SCons.Tool
import SCons.Util
from SCons.Action import Action, CommandAction
from SCons.Defaults import StaticObjectEmitter, SharedObjectEmitter


def isfortran(env, source) -> bool:
    """Returns True if *source* has any fortran files in it.

    Only checks based on filename suffixes, does not examine code.
    """
    try:
        fsuffixes = env['FORTRANSUFFIXES']
    except KeyError:
        # If no FORTRANSUFFIXES, no fortran tool, so there is no need to look
        # for fortran sources.
        return False

    if not source:
        # Source might be None for unusual cases like SConf.
        return False
    for s in source:
        if s.sources:
            ext = os.path.splitext(str(s.sources[0]))[1]
            if ext in fsuffixes:
                return True
    return False


def _fortranEmitter(target, source, env) -> Tuple:
    """Common code for Fortran emitter.

    Called by both the static and shared object emitters,
    mainly to account for generated module files.
    """
    node = source[0].rfile()
    if not node.exists() and not node.is_derived():
        print("Could not locate " + str(node.name))
        return [], []

    # This has to match the def_regex in the Fortran scanner
    mod_regex = r"""(?i)^\s*MODULE\s+(?!PROCEDURE|SUBROUTINE|FUNCTION|PURE|ELEMENTAL)(\w+)"""
    cre = re.compile(mod_regex, re.M)
    # Retrieve all USE'd module names
    modules = cre.findall(node.get_text_contents())
    # Remove unique items from the list
    modules = SCons.Util.unique(modules)
    # Convert module name to a .mod filename
    suffix = env.subst('$FORTRANMODSUFFIX', target=target, source=source)
    moddir = env.subst('$FORTRANMODDIR', target=target, source=source)
    modules = [mod.lower() + suffix for mod in modules]
    for module in modules:
        target.append(env.fs.File(module, moddir))
    return target, source


def FortranEmitter(target, source, env) -> Tuple:
    """Create emitter for static objects."""
    target, source = _fortranEmitter(target, source, env)
    return StaticObjectEmitter(target, source, env)


def ShFortranEmitter(target, source, env) -> Tuple:
    """Create emitter for shared objects."""
    target, source = _fortranEmitter(target, source, env)
    return SharedObjectEmitter(target, source, env)


def ComputeFortranSuffixes(suffixes: List[str], ppsuffixes: List[str]) -> None:
    """Update the suffix lists to reflect the platform requirements.

    If upper-cased suffixes can be distinguished from lower, those are
    added to *ppsuffixes*. If not, they are added to *suffixes*.

    Args:
        suffixes: regular Fortran source files
        ppsuffixes: Fortran source files that should be
          be run through the pre-processor
    """
    assert len(suffixes) > 0
    s = suffixes[0]
    sup = s.upper()
    upper_suffixes = [suf.upper() for suf in suffixes]
    if SCons.Util.case_sensitive_suffixes(s, sup):
        ppsuffixes.extend(upper_suffixes)
    else:
        suffixes.extend(upper_suffixes)


def CreateDialectActions(
    dialect: str,
) -> Tuple[CommandAction, CommandAction, CommandAction, CommandAction]:
    """Create dialect specific actions."""
    CompAction = Action(f'${dialect}COM ', cmdstr=f'${dialect}COMSTR')
    CompPPAction = Action(f'${dialect}PPCOM ', cmdstr=f'${dialect}PPCOMSTR')
    ShCompAction = Action(f'$SH{dialect}COM ', cmdstr=f'$SH{dialect}COMSTR')
    ShCompPPAction = Action(f'$SH{dialect}PPCOM ', cmdstr=f'$SH{dialect}PPCOMSTR')
    return CompAction, CompPPAction, ShCompAction, ShCompPPAction


def DialectAddToEnv(
    env,
    dialect: str,
    suffixes: List[str],
    ppsuffixes: List[str],
    support_mods: bool = False,
) -> None:
    """Add dialect specific construction variables.

    Args:
        dialect: dialect name
        suffixes: suffixes associated with this dialect
        ppsuffixes: suffixes using cpp associated with this dialect
        support_mods: whether this dialect supports modules
    """
    ComputeFortranSuffixes(suffixes, ppsuffixes)

    fscan = SCons.Scanner.Fortran.FortranScan(f"{dialect}PATH")
    for suffix in suffixes + ppsuffixes:
        SCons.Tool.SourceFileScanner.add_scanner(suffix, fscan)

    env.AppendUnique(FORTRANSUFFIXES=suffixes + ppsuffixes)

    compaction, compppaction, shcompaction, shcompppaction = \
            CreateDialectActions(dialect)
    static_obj, shared_obj = SCons.Tool.createObjBuilders(env)

    for suffix in suffixes:
        static_obj.add_action(suffix, compaction)
        shared_obj.add_action(suffix, shcompaction)
        static_obj.add_emitter(suffix, FortranEmitter)
        shared_obj.add_emitter(suffix, ShFortranEmitter)

    for suffix in ppsuffixes:
        static_obj.add_action(suffix, compppaction)
        shared_obj.add_action(suffix, shcompppaction)
        static_obj.add_emitter(suffix, FortranEmitter)
        shared_obj.add_emitter(suffix, ShFortranEmitter)

    if f'{dialect}FLAGS' not in env:
        env[f'{dialect}FLAGS'] = SCons.Util.CLVar('')
    if f'SH{dialect}FLAGS' not in env:
        env[f'SH{dialect}FLAGS'] = SCons.Util.CLVar(f'${dialect}FLAGS')

    # If a tool does not define fortran prefix/suffix for include path, use C ones
    if f'INC{dialect}PREFIX' not in env:
        env[f'INC{dialect}PREFIX'] = '$INCPREFIX'
    if f'INC{dialect}SUFFIX' not in env:
        env[f'INC{dialect}SUFFIX'] = '$INCSUFFIX'

    env[f'_{dialect}INCFLAGS'] = f'${{_concat(INC{dialect}PREFIX, {dialect}PATH, INC{dialect}SUFFIX, __env__, RDirs, TARGET, SOURCE, affect_signature=False)}}'

    if support_mods:
        env[f'{dialect}COM'] = f'${dialect} -o $TARGET -c $FORTRANCOMMONFLAGS ${dialect}FLAGS $_{dialect}INCFLAGS $_FORTRANMODFLAG $SOURCES'
        env[f'{dialect}PPCOM'] = f'${dialect} -o $TARGET -c $FORTRANCOMMONFLAGS ${dialect}FLAGS $CPPFLAGS $_CPPDEFFLAGS $_{dialect}INCFLAGS $_FORTRANMODFLAG $SOURCES'
        env[f'SH{dialect}COM'] = f'$SH{dialect} -o $TARGET -c $FORTRANCOMMONFLAGS $SH{dialect}FLAGS $_{dialect}INCFLAGS $_FORTRANMODFLAG $SOURCES'
        env[f'SH{dialect}PPCOM'] = f'$SH{dialect} -o $TARGET -c $FORTRANCOMMONFLAGS $SH{dialect}FLAGS $CPPFLAGS $_CPPDEFFLAGS $_{dialect}INCFLAGS $_FORTRANMODFLAG $SOURCES'
    else:
        env[f'{dialect}COM'] = f'${dialect} -o $TARGET -c $FORTRANCOMMONFLAGS ${dialect}FLAGS $_{dialect}INCFLAGS $SOURCES'
        env[f'{dialect}PPCOM'] = f'${dialect} -o $TARGET -c $FORTRANCOMMONFLAGS ${dialect}FLAGS $CPPFLAGS $_CPPDEFFLAGS $_{dialect}INCFLAGS $SOURCES'
        env[f'SH{dialect}COM'] = f'$SH{dialect} -o $TARGET -c $FORTRANCOMMONFLAGS $SH{dialect}FLAGS $_{dialect}INCFLAGS $SOURCES'
        env[f'SH{dialect}PPCOM'] = f'$SH{dialect} -o $TARGET -c $FORTRANCOMMONFLAGS $SH{dialect}FLAGS $CPPFLAGS $_CPPDEFFLAGS $_{dialect}INCFLAGS $SOURCES'


def add_fortran_to_env(env) -> None:
    """Add Builders and construction variables for Fortran/generic."""
    FortranSuffixes = env.get('FORTRANFILESUFFIXES', ['.f', '.for', '.ftn'])
    FortranPPSuffixes = env.get('FORTRANPPFILESUFFIXES', ['.fpp', '.FPP'])
    DialectAddToEnv(env, "FORTRAN", FortranSuffixes, FortranPPSuffixes, support_mods=True)

    # Module support
    env['FORTRANMODPREFIX'] = ''     # like $LIBPREFIX
    env['FORTRANMODSUFFIX'] = '.mod' # like $LIBSUFFIX
    env['FORTRANMODDIR'] = ''          # where the compiler should place .mod files
    env['FORTRANMODDIRPREFIX'] = ''    # some prefix to $FORTRANMODDIR - similar to $INCPREFIX
    env['FORTRANMODDIRSUFFIX'] = ''    # some suffix to $FORTRANMODDIR - similar to $INCSUFFIX
    env['_FORTRANMODFLAG'] = '$( ${_concat(FORTRANMODDIRPREFIX, FORTRANMODDIR, FORTRANMODDIRSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)'

def add_f77_to_env(env) -> None:
    """Add Builders and construction variables for f77 dialect."""
    F77Suffixes = env.get('F77FILESUFFIXES', ['.f77'])
    F77PPSuffixes = env.get('F77PPFILESUFFIXES', [])
    DialectAddToEnv(env, "F77", F77Suffixes, F77PPSuffixes)

def add_f90_to_env(env) -> None:
    """Add Builders and construction variables for f90 dialect."""
    F90Suffixes = env.get('F90FILESUFFIXES', ['.f90'])
    F90PPSuffixes = env.get('F90PPFILESUFFIXES', [])
    DialectAddToEnv(env, "F90", F90Suffixes, F90PPSuffixes, support_mods=True)

def add_f95_to_env(env) -> None:
    """Add Builders and construction variables for f95 dialect."""
    F95Suffixes = env.get('F95FILESUFFIXES', ['.f95'])
    F95PPSuffixes = env.get('F95PPFILESUFFIXES', [])
    DialectAddToEnv(env, "F95", F95Suffixes, F95PPSuffixes, support_mods=True)

def add_f03_to_env(env) -> None:
    """Add Builders and construction variables for f03 dialect."""
    F03Suffixes = env.get('F03FILESUFFIXES', ['.f03'])
    F03PPSuffixes = env.get('F03PPFILESUFFIXES', [])
    DialectAddToEnv(env, "F03", F03Suffixes, F03PPSuffixes, support_mods=True)

def add_f08_to_env(env) -> None:
    """Add Builders and construction variables for f08 dialect."""
    F08Suffixes = env.get('F08FILESUFFIXES', ['.f08'])
    F08PPSuffixes = env.get('F08PPFILESUFFIXES', [])
    DialectAddToEnv(env, "F08", F08Suffixes, F08PPSuffixes, support_mods=True)

def add_all_to_env(env) -> None:
    """Add builders and construction variables for all supported dialects."""
    add_fortran_to_env(env)
    add_f77_to_env(env)
    add_f90_to_env(env)
    add_f95_to_env(env)
    add_f03_to_env(env)
    add_f08_to_env(env)

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