import itertools
from time import time

import Errors
import DebugFlags
import Options
from Errors import PyrexError, CompileError, InternalError, AbortError, error

#
# Really small pipeline stages
#
def dumptree(t):
    # For quick debugging in pipelines
    print t.dump()
    return t

def abort_on_errors(node):
    # Stop the pipeline if there are any errors.
    if Errors.num_errors != 0:
        raise AbortError, "pipeline break"
    return node

def parse_stage_factory(context):
    def parse(compsrc):
        source_desc = compsrc.source_desc
        full_module_name = compsrc.full_module_name
        initial_pos = (source_desc, 1, 0)
        saved_cimport_from_pyx, Options.cimport_from_pyx = Options.cimport_from_pyx, False
        scope = context.find_module(full_module_name, pos = initial_pos, need_pxd = 0,
                                    check_module_name = not Options.embed)
        Options.cimport_from_pyx = saved_cimport_from_pyx
        tree = context.parse(source_desc, scope, pxd = 0, full_module_name = full_module_name)
        tree.compilation_source = compsrc
        tree.scope = scope
        tree.is_pxd = False
        return tree
    return parse

def parse_pxd_stage_factory(context, scope, module_name):
    def parse(source_desc):
        tree = context.parse(source_desc, scope, pxd=True,
                             full_module_name=module_name)
        tree.scope = scope
        tree.is_pxd = True
        return tree
    return parse

def generate_pyx_code_stage_factory(options, result):
    def generate_pyx_code_stage(module_node):
        module_node.process_implementation(options, result)
        result.compilation_source = module_node.compilation_source
        return result
    return generate_pyx_code_stage

def inject_pxd_code_stage_factory(context):
    def inject_pxd_code_stage(module_node):
        from textwrap import dedent
        stats = module_node.body.stats
        for name, (statlistnode, scope) in context.pxds.iteritems():
            module_node.merge_in(statlistnode, scope)
        return module_node
    return inject_pxd_code_stage

def use_utility_code_definitions(scope, target):
    for entry in scope.entries.itervalues():
        if entry.used and entry.utility_code_definition:
            target.use_utility_code(entry.utility_code_definition)
            for required_utility in entry.utility_code_definition.requires:
                target.use_utility_code(required_utility)
        elif entry.as_module:
            use_utility_code_definitions(entry.as_module, target)

def inject_utility_code_stage_factory(context):
    def inject_utility_code_stage(module_node):
        # First, make sure any utility code pulled in by using symbols in the cython
        # scope is included
        use_utility_code_definitions(context.cython_scope, module_node.scope)

        added = []
        # Note: the list might be extended inside the loop (if some utility code
        # pulls in other utility code)
        for utilcode in module_node.scope.utility_code_list:
            if utilcode in added: continue
            added.append(utilcode)
            tree = utilcode.get_tree()
            if tree:
                module_node.merge_in(tree.body, tree.scope, merge_scope=True)
        return module_node
    return inject_utility_code_stage

#
# Pipeline factories
#

def create_pipeline(context, mode, exclude_classes=()):
    assert mode in ('pyx', 'py', 'pxd')
    from Visitor import PrintTree
    from ParseTreeTransforms import WithTransform, NormalizeTree, PostParse, PxdPostParse
    from ParseTreeTransforms import ForwardDeclareTypes, AnalyseDeclarationsTransform
    from ParseTreeTransforms import AnalyseExpressionsTransform
    from ParseTreeTransforms import CreateClosureClasses, MarkClosureVisitor, DecoratorTransform
    from ParseTreeTransforms import InterpretCompilerDirectives, TransformBuiltinMethods
    from ParseTreeTransforms import ExpandInplaceOperators, ParallelRangeTransform
    from TypeInference import MarkAssignments, MarkOverflowingArithmetic
    from ParseTreeTransforms import AdjustDefByDirectives, AlignFunctionDefinitions
    from ParseTreeTransforms import RemoveUnreachableCode, GilCheck
    from FlowControl import CreateControlFlowGraph
    from AnalysedTreeTransforms import AutoTestDictTransform
    from AutoDocTransforms import EmbedSignature
    from Optimize import FlattenInListTransform, SwitchTransform, IterationTransform
    from Optimize import EarlyReplaceBuiltinCalls, OptimizeBuiltinCalls
    from Optimize import ConstantFolding, FinalOptimizePhase
    from Optimize import DropRefcountingTransform
    from Buffer import IntroduceBufferAuxiliaryVars
    from ModuleNode import check_c_declarations, check_c_declarations_pxd

    if mode == 'pxd':
        _check_c_declarations = check_c_declarations_pxd
        _specific_post_parse = PxdPostParse(context)
    else:
        _check_c_declarations = check_c_declarations
        _specific_post_parse = None

    if mode == 'py':
        _align_function_definitions = AlignFunctionDefinitions(context)
    else:
        _align_function_definitions = None

    # NOTE: This is the "common" parts of the pipeline, which is also
    # code in pxd files. So it will be run multiple times in a
    # compilation stage.
    stages = [
        NormalizeTree(context),
        PostParse(context),
        _specific_post_parse,
        InterpretCompilerDirectives(context, context.compiler_directives),
        ParallelRangeTransform(context),
        AdjustDefByDirectives(context),
        MarkClosureVisitor(context),
        _align_function_definitions,
        RemoveUnreachableCode(context),
        ConstantFolding(),
        FlattenInListTransform(),
        WithTransform(context),
        DecoratorTransform(context),
        ForwardDeclareTypes(context),
        AnalyseDeclarationsTransform(context),
        AutoTestDictTransform(context),
        EmbedSignature(context),
        EarlyReplaceBuiltinCalls(context),  ## Necessary?
        TransformBuiltinMethods(context),  ## Necessary?
        MarkAssignments(context),
        CreateControlFlowGraph(context),
        RemoveUnreachableCode(context),
        # MarkAssignments(context),
        MarkOverflowingArithmetic(context),
        IntroduceBufferAuxiliaryVars(context),
        _check_c_declarations,
        AnalyseExpressionsTransform(context),
        CreateClosureClasses(context),  ## After all lookups and type inference
        ExpandInplaceOperators(context),
        OptimizeBuiltinCalls(context),  ## Necessary?
        IterationTransform(),
        SwitchTransform(),
        DropRefcountingTransform(),
        FinalOptimizePhase(context),
        GilCheck(),
        ]
    filtered_stages = []
    for s in stages:
        if s.__class__ not in exclude_classes:
            filtered_stages.append(s)
    return filtered_stages

def create_pyx_pipeline(context, options, result, py=False, exclude_classes=()):
    if py:
        mode = 'py'
    else:
        mode = 'pyx'
    test_support = []
    if options.evaluate_tree_assertions:
        from Cython.TestUtils import TreeAssertVisitor
        test_support.append(TreeAssertVisitor())

    if options.gdb_debug:
        from Cython.Debugger import DebugWriter
        from ParseTreeTransforms import DebugTransform
        context.gdb_debug_outputwriter = DebugWriter.CythonDebugWriter(
            options.output_dir)
        debug_transform = [DebugTransform(context, options, result)]
    else:
        debug_transform = []

    return list(itertools.chain(
        [parse_stage_factory(context)],
        create_pipeline(context, mode, exclude_classes=exclude_classes),
        test_support,
        [inject_pxd_code_stage_factory(context),
         inject_utility_code_stage_factory(context),
         abort_on_errors],
        debug_transform,
        [generate_pyx_code_stage_factory(options, result)]))

def create_pxd_pipeline(context, scope, module_name):
    from CodeGeneration import ExtractPxdCode

    # The pxd pipeline ends up with a CCodeWriter containing the
    # code of the pxd, as well as a pxd scope.
    return [
        parse_pxd_stage_factory(context, scope, module_name)
        ] + create_pipeline(context, 'pxd') + [
        ExtractPxdCode(context)
        ]

def create_py_pipeline(context, options, result):
    return create_pyx_pipeline(context, options, result, py=True)

def create_pyx_as_pxd_pipeline(context, result):
    from ParseTreeTransforms import AlignFunctionDefinitions, \
        MarkClosureVisitor, WithTransform, AnalyseDeclarationsTransform
    from Optimize import ConstantFolding, FlattenInListTransform
    from Nodes import StatListNode
    pipeline = []
    pyx_pipeline = create_pyx_pipeline(context, context.options, result,
                                       exclude_classes=[
                                           AlignFunctionDefinitions,
                                           MarkClosureVisitor,
                                           ConstantFolding,
                                           FlattenInListTransform,
                                           WithTransform
                                           ])
    for stage in pyx_pipeline:
        pipeline.append(stage)
        if isinstance(stage, AnalyseDeclarationsTransform):
            # This is the last stage we need.
            break
    def fake_pxd(root):
        for entry in root.scope.entries.values():
            entry.defined_in_pxd = 1
        return StatListNode(root.pos, stats=[]), root.scope
    pipeline.append(fake_pxd)
    return pipeline

def insert_into_pipeline(pipeline, transform, before=None, after=None):
    """
    Insert a new transform into the pipeline after or before an instance of
    the given class. e.g.

        pipeline = insert_into_pipeline(pipeline, transform,
                                        after=AnalyseDeclarationsTransform)
    """
    assert before or after

    cls = before or after
    for i, t in enumerate(pipeline):
        if isinstance(t, cls):
            break

    if after:
        i += 1

    return pipeline[:i] + [transform] + pipeline[i:]

#
# Running a pipeline
#

def run_pipeline(pipeline, source):
    error = None
    data = source
    try:
        try:
            for phase in pipeline:
                if phase is not None:
                    if DebugFlags.debug_verbose_pipeline:
                        t = time()
                        print "Entering pipeline phase %r" % phase
                    data = phase(data)
                    if DebugFlags.debug_verbose_pipeline:
                        print "    %.3f seconds" % (time() - t)
        except CompileError, err:
            # err is set
            Errors.report_error(err)
            error = err
    except InternalError, err:
        # Only raise if there was not an earlier error
        if Errors.num_errors == 0:
            raise
        error = err
    except AbortError, err:
        error = err
    return (error, data)
