package cimport

import "../target"
import "base:runtime"
import "core:dynlib"
import "core:fmt"
import "core:mem"
import "core:os/os2"
import "core:strings"

CXCursor :: struct {
	kind:  i32,
	xdata: i32,
	data:  [3]rawptr,
}

CXType :: struct {
	kind: i32,
	data: [2]rawptr,
}

CXString :: struct {
	data:          rawptr,
	private_flags: u32,
}

CXIndex :: distinct rawptr
CXTranslationUnit :: distinct rawptr
CXDiagnostic :: distinct rawptr

Cursor_Visitor :: proc "c"(cursor, parent: CXCursor, client_data: rawptr) -> i32

Api :: struct {
	library: dynlib.Library,

	create_index:                  proc "c"(i32, i32) -> CXIndex,
	dispose_index:                 proc "c"(CXIndex),
	parse_translation_unit:        proc "c"(CXIndex, cstring, [^]cstring, i32, rawptr, u32, u32, ^CXTranslationUnit) -> i32,
	dispose_translation_unit:      proc "c"(CXTranslationUnit),
	get_translation_unit_cursor:  proc "c"(CXTranslationUnit) -> CXCursor,
	visit_children:                proc "c"(CXCursor, Cursor_Visitor, rawptr) -> u32,
	get_cursor_kind:               proc "c"(CXCursor) -> i32,
	get_cursor_spelling:           proc "c"(CXCursor) -> CXString,
	get_cursor_usr:                proc "c"(CXCursor) -> CXString,
	get_cursor_linkage:            proc "c"(CXCursor) -> i32,
	get_cursor_type:               proc "c"(CXCursor) -> CXType,
	get_typedef_underlying_type:   proc "c"(CXCursor) -> CXType,
	get_type_declaration:          proc "c"(CXType) -> CXCursor,
	get_canonical_type:            proc "c"(CXType) -> CXType,
	get_pointee_type:              proc "c"(CXType) -> CXType,
	get_result_type:               proc "c"(CXType) -> CXType,
	get_num_arg_types:             proc "c"(CXType) -> i32,
	get_arg_type:                  proc "c"(CXType, u32) -> CXType,
	is_const_qualified_type:       proc "c"(CXType) -> u32,
	is_volatile_qualified_type:    proc "c"(CXType) -> u32,
	cursor_is_variadic:            proc "c"(CXCursor) -> u32,
	get_num_diagnostics:           proc "c"(CXTranslationUnit) -> u32,
	get_diagnostic:                proc "c"(CXTranslationUnit, u32) -> CXDiagnostic,
	get_diagnostic_severity:       proc "c"(CXDiagnostic) -> i32,
	get_diagnostic_spelling:       proc "c"(CXDiagnostic) -> CXString,
	dispose_diagnostic:            proc "c"(CXDiagnostic),
	get_cstring:                   proc "c"(CXString) -> cstring,
	dispose_string:                proc "c"(CXString),
}

CXCursor_StructDecl :: i32(2)
CXCursor_UnionDecl :: i32(3)
CXCursor_EnumDecl :: i32(5)
CXCursor_FunctionDecl :: i32(8)
CXCursor_VarDecl :: i32(9)
CXCursor_TypedefDecl :: i32(20)
CXCursor_MacroDefinition :: i32(501)

CXLinkage_External :: i32(4)

CXType_Invalid :: i32(0)
CXType_Unexposed :: i32(1)
CXType_Void :: i32(2)
CXType_Char_U :: i32(4)
CXType_UChar :: i32(5)
CXType_UShort :: i32(8)
CXType_UInt :: i32(9)
CXType_ULong :: i32(10)
CXType_ULongLong :: i32(11)
CXType_Char_S :: i32(13)
CXType_SChar :: i32(14)
CXType_Short :: i32(16)
CXType_Int :: i32(17)
CXType_Long :: i32(18)
CXType_LongLong :: i32(19)
CXType_Float :: i32(21)
CXType_Double :: i32(22)
CXType_LongDouble :: i32(23)
CXType_Pointer :: i32(101)
CXType_Record :: i32(105)
CXType_Enum :: i32(106)
CXType_Typedef :: i32(107)
CXType_FunctionNoProto :: i32(110)
CXType_FunctionProto :: i32(111)
CXType_Elaborated :: i32(119)
CXType_Attributed :: i32(163)

CXChildVisit_Continue :: i32(1)

CXTranslationUnit_DetailedPreprocessingRecord :: u32(0x01)
CXTranslationUnit_SkipFunctionBodies :: u32(0x40)
CXTranslationUnit_KeepGoing :: u32(0x200)

CXDiagnostic_Error :: i32(3)

load_proc :: proc(api: ^Api, name: string, destination: ^$T) -> bool {
	address, found := dynlib.symbol_address(api.library, name)
	if !found {
		return false
	}
	destination^ = transmute(T)address
	return true
}

load_api_from :: proc(path: string) -> (Api, bool) {
	api: Api
	library, loaded := dynlib.load_library(path)
	if !loaded {
		return {}, false
	}
	api.library = library
	ok :=
		load_proc(&api, "clang_createIndex", &api.create_index) &&
		load_proc(&api, "clang_disposeIndex", &api.dispose_index) &&
		load_proc(&api, "clang_parseTranslationUnit2", &api.parse_translation_unit) &&
		load_proc(&api, "clang_disposeTranslationUnit", &api.dispose_translation_unit) &&
		load_proc(&api, "clang_getTranslationUnitCursor", &api.get_translation_unit_cursor) &&
		load_proc(&api, "clang_visitChildren", &api.visit_children) &&
		load_proc(&api, "clang_getCursorKind", &api.get_cursor_kind) &&
		load_proc(&api, "clang_getCursorSpelling", &api.get_cursor_spelling) &&
		load_proc(&api, "clang_getCursorUSR", &api.get_cursor_usr) &&
		load_proc(&api, "clang_getCursorLinkage", &api.get_cursor_linkage) &&
		load_proc(&api, "clang_getCursorType", &api.get_cursor_type) &&
		load_proc(&api, "clang_getTypedefDeclUnderlyingType", &api.get_typedef_underlying_type) &&
		load_proc(&api, "clang_getTypeDeclaration", &api.get_type_declaration) &&
		load_proc(&api, "clang_getCanonicalType", &api.get_canonical_type) &&
		load_proc(&api, "clang_getPointeeType", &api.get_pointee_type) &&
		load_proc(&api, "clang_getResultType", &api.get_result_type) &&
		load_proc(&api, "clang_getNumArgTypes", &api.get_num_arg_types) &&
		load_proc(&api, "clang_getArgType", &api.get_arg_type) &&
		load_proc(&api, "clang_isConstQualifiedType", &api.is_const_qualified_type) &&
		load_proc(&api, "clang_isVolatileQualifiedType", &api.is_volatile_qualified_type) &&
		load_proc(&api, "clang_Cursor_isVariadic", &api.cursor_is_variadic) &&
		load_proc(&api, "clang_getNumDiagnostics", &api.get_num_diagnostics) &&
		load_proc(&api, "clang_getDiagnostic", &api.get_diagnostic) &&
		load_proc(&api, "clang_getDiagnosticSeverity", &api.get_diagnostic_severity) &&
		load_proc(&api, "clang_getDiagnosticSpelling", &api.get_diagnostic_spelling) &&
		load_proc(&api, "clang_disposeDiagnostic", &api.dispose_diagnostic) &&
		load_proc(&api, "clang_getCString", &api.get_cstring) &&
		load_proc(&api, "clang_disposeString", &api.dispose_string)
	if !ok {
		_ = dynlib.unload_library(api.library)
		return {}, false
	}
	return api, true
}

load_api :: proc() -> (Api, bool) {
	if override, found := os2.lookup_env_alloc("BROLANG_LIBCLANG_PATH", context.temp_allocator); found {
		if api, ok := load_api_from(override); ok {
			return api, true
		}
	}
	candidates := [?]string{
		"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/libclang.dylib",
		"/Library/Developer/CommandLineTools/usr/lib/libclang.dylib",
		"/opt/homebrew/opt/llvm/lib/libclang.dylib",
		"/opt/homebrew/opt/llvm@21/lib/libclang.dylib",
		"libclang.dylib",
		"libclang.so",
	}
	for candidate in candidates {
		if api, ok := load_api_from(candidate); ok {
			return api, true
		}
	}
	return {}, false
}

clone_cx_string :: proc(api: ^Api, value: CXString, allocator: mem.Allocator) -> string {
	defer api.dispose_string(value)
	text := api.get_cstring(value)
	if text == nil {
		return fmt.aprintf("", allocator=allocator)
	}
	return fmt.aprintf("%s", string(text), allocator=allocator)
}

Context :: struct {
	api:       ^Api,
	result:    ^Result,
	allocator: mem.Allocator,
}

add_type :: proc(ctx: ^Context, value: Type) -> Type_Id {
	id := Type_Id(len(ctx.result.types))
	append(&ctx.result.types, value)
	return id
}

find_record :: proc(ctx: ^Context, identity: string) -> (u32, bool) {
	for record, index in ctx.result.records {
		if record.identity == identity {
			return u32(index), true
		}
	}
	return 0, false
}

add_record :: proc(ctx: ^Context, declaration: CXCursor, preferred_name: string) -> u32 {
	identity := clone_cx_string(ctx.api, ctx.api.get_cursor_usr(declaration), ctx.allocator)
	if len(identity) == 0 {
		delete(identity, ctx.allocator)
		identity = clone_cx_string(ctx.api, ctx.api.get_cursor_spelling(declaration), ctx.allocator)
	}
	if index, ok := find_record(ctx, identity); ok {
		delete(identity, ctx.allocator)
		return index
	}
	name := fmt.aprintf("%s", preferred_name, allocator=ctx.allocator)
	if len(name) == 0 {
		delete(name, ctx.allocator)
		name = clone_cx_string(ctx.api, ctx.api.get_cursor_spelling(declaration), ctx.allocator)
	}
	index := u32(len(ctx.result.records))
	append(&ctx.result.records, Record{name=name, identity=identity})
	return index
}

translate_type :: proc(ctx: ^Context, value: CXType, preferred_record_name := "", depth := 0) -> Type_Id {
	if depth > 64 || value.kind == CXType_Invalid || ctx.api.is_volatile_qualified_type(value) != 0 {
		return INVALID_TYPE
	}
	switch value.kind {
	case CXType_Void:       return add_type(ctx, Type{kind=.Void, child=INVALID_TYPE})
	case CXType_Char_U:     return add_type(ctx, Type{kind=.C_Char, child=INVALID_TYPE})
	case CXType_Char_S:     return add_type(ctx, Type{kind=.C_Char, child=INVALID_TYPE})
	case CXType_SChar:      return add_type(ctx, Type{kind=.C_Schar, child=INVALID_TYPE})
	case CXType_UChar:      return add_type(ctx, Type{kind=.C_Uchar, child=INVALID_TYPE})
	case CXType_Short:      return add_type(ctx, Type{kind=.C_Short, child=INVALID_TYPE})
	case CXType_UShort:     return add_type(ctx, Type{kind=.C_Ushort, child=INVALID_TYPE})
	case CXType_Int:        return add_type(ctx, Type{kind=.C_Int, child=INVALID_TYPE})
	case CXType_UInt:       return add_type(ctx, Type{kind=.C_Uint, child=INVALID_TYPE})
	case CXType_Long:       return add_type(ctx, Type{kind=.C_Long, child=INVALID_TYPE})
	case CXType_ULong:      return add_type(ctx, Type{kind=.C_Ulong, child=INVALID_TYPE})
	case CXType_LongLong:   return add_type(ctx, Type{kind=.C_Longlong, child=INVALID_TYPE})
	case CXType_ULongLong:  return add_type(ctx, Type{kind=.C_Ulonglong, child=INVALID_TYPE})
	case CXType_Float:      return add_type(ctx, Type{kind=.C_Float, child=INVALID_TYPE})
	case CXType_Double:     return add_type(ctx, Type{kind=.C_Double, child=INVALID_TYPE})
	case CXType_LongDouble: return add_type(ctx, Type{kind=.C_Longdouble, child=INVALID_TYPE})
	case CXType_Pointer:
		pointee := ctx.api.get_pointee_type(value)
		child := translate_type(ctx, pointee, "", depth+1)
		if child == INVALID_TYPE {
			return INVALID_TYPE
		}
		return add_type(ctx, Type{
			kind=.Pointer,
			child=child,
			mutable=ctx.api.is_const_qualified_type(pointee) == 0,
		})
	case CXType_Record:
		declaration := ctx.api.get_type_declaration(value)
		if ctx.api.get_cursor_kind(declaration) == CXCursor_UnionDecl {
			return INVALID_TYPE
		}
		record := add_record(ctx, declaration, preferred_record_name)
		return add_type(ctx, Type{kind=.Record, child=INVALID_TYPE, record=record})
	case CXType_Typedef:
		declaration := ctx.api.get_type_declaration(value)
		name := clone_cx_string(ctx.api, ctx.api.get_cursor_spelling(declaration), ctx.allocator)
		defer delete(name, ctx.allocator)
		return translate_type(ctx, ctx.api.get_typedef_underlying_type(declaration), name, depth+1)
	case CXType_Elaborated, CXType_Attributed, CXType_Unexposed:
		canonical := ctx.api.get_canonical_type(value)
		if canonical.kind == value.kind {
			return INVALID_TYPE
		}
		return translate_type(ctx, canonical, preferred_record_name, depth+1)
	case CXType_Enum, CXType_FunctionNoProto, CXType_FunctionProto:
		return INVALID_TYPE
	}
	return INVALID_TYPE
}

has_named :: proc(items: []Unsupported, name: string) -> bool {
	for item in items {
		if item.name == name {
			return true
		}
	}
	return false
}

add_unsupported :: proc(ctx: ^Context, name, reason: string) {
	if len(name) == 0 || strings.has_prefix(name, "__") || has_named(ctx.result.unsupported[:], name) {
		return
	}
	append(&ctx.result.unsupported, Unsupported{
		name=fmt.aprintf("%s", name, allocator=ctx.allocator),
		reason=fmt.aprintf("%s", reason, allocator=ctx.allocator),
	})
}

add_alias :: proc(ctx: ^Context, name: string, value: Type_Id, reason := "") {
	if len(name) == 0 {
		return
	}
	for alias in ctx.result.aliases {
		if alias.name == name {
			return
		}
	}
	append(&ctx.result.aliases, Alias{
		name=fmt.aprintf("%s", name, allocator=ctx.allocator),
		type=value,
		reason=fmt.aprintf("%s", reason, allocator=ctx.allocator),
	})
}

visit_cursor :: proc "c"(cursor, parent: CXCursor, client_data: rawptr) -> i32 {
	context = runtime.default_context()
	ctx := (^Context)(client_data)
	kind := ctx.api.get_cursor_kind(cursor)
	name := clone_cx_string(ctx.api, ctx.api.get_cursor_spelling(cursor), ctx.allocator)
	defer delete(name, ctx.allocator)
	switch kind {
	case CXCursor_FunctionDecl:
		if len(name) == 0 {
			return CXChildVisit_Continue
		}
		reason := ""
		linkage := ctx.api.get_cursor_linkage(cursor)
		if linkage != CXLinkage_External {
			reason = "static and non-external C functions are not supported"
		}
		variadic := ctx.api.cursor_is_variadic(cursor) != 0
		function_type := ctx.api.get_cursor_type(cursor)
		result_type := translate_type(ctx, ctx.api.get_result_type(function_type))
		if result_type == INVALID_TYPE && len(reason) == 0 {
			reason = "function result type is not supported"
		}
		params: [dynamic]Type_Id
		params.allocator = ctx.allocator
		count := ctx.api.get_num_arg_types(function_type)
		if count < 0 {
			reason = "function declaration has no prototype"
		} else {
			for index in 0..<count {
				param := translate_type(ctx, ctx.api.get_arg_type(function_type, u32(index)))
				append(&params, param)
				if param == INVALID_TYPE && len(reason) == 0 {
					reason = "function parameter type is not supported"
				}
			}
		}
		append(&ctx.result.functions, Function{
			name=fmt.aprintf("%s", name, allocator=ctx.allocator),
			params=params[:],
			result=result_type,
			variadic=variadic,
			reason=fmt.aprintf("%s", reason, allocator=ctx.allocator),
		})
	case CXCursor_TypedefDecl:
		value := translate_type(ctx, ctx.api.get_typedef_underlying_type(cursor), name)
		reason := ""
		if value == INVALID_TYPE {
			reason = "typedef underlying type is not supported"
		}
		add_alias(ctx, name, value, reason)
	case CXCursor_StructDecl:
		if len(name) > 0 {
			record := add_record(ctx, cursor, name)
			value := add_type(ctx, Type{kind=.Record, child=INVALID_TYPE, record=record})
			add_alias(ctx, name, value)
		}
	case CXCursor_UnionDecl:
		add_unsupported(ctx, name, "C unions are not supported")
	case CXCursor_EnumDecl:
		add_unsupported(ctx, name, "C enums are not supported")
	case CXCursor_VarDecl:
		add_unsupported(ctx, name, "external C variables are not supported")
	case CXCursor_MacroDefinition:
		add_unsupported(ctx, name, "C macros are not supported")
	case:
	}
	return CXChildVisit_Continue
}

import_with_libclang :: proc(_: rawptr, request: Request, allocator: mem.Allocator) -> Result {
	result := init_result(allocator)
	api, loaded := load_api()
	if !loaded {
		result.infrastructure = true
		result.error_message = fmt.aprintf(
			"could not load libclang; set BROLANG_LIBCLANG_PATH to a compatible library",
			allocator=allocator,
		)
		return result
	}
	defer _ = dynlib.unload_library(api.library)

	index := api.create_index(1, 0)
	if index == nil {
		result.infrastructure = true
		result.error_message = fmt.aprintf("could not create libclang index", allocator=allocator)
		return result
	}
	defer api.dispose_index(index)

	arguments: [dynamic]string
	arguments.allocator = context.temp_allocator
	append(&arguments, "-x", "c", "-target", target.llvm_triple(request.target))
	for path in request.include_paths {
		append(&arguments, fmt.tprintf("-I%s", path))
	}
	for define in request.defines {
		append(&arguments, fmt.tprintf("-D%s", define))
	}
	c_arguments := make([]cstring, len(arguments), context.temp_allocator)
	for argument, argument_index in arguments {
		c_arguments[argument_index] = strings.clone_to_cstring(argument, context.temp_allocator)
	}
	c_path := strings.clone_to_cstring(request.path, context.temp_allocator)
	translation_unit: CXTranslationUnit
	error_code := api.parse_translation_unit(
		index,
		c_path,
		raw_data(c_arguments),
		i32(len(c_arguments)),
		nil,
		0,
		CXTranslationUnit_DetailedPreprocessingRecord | CXTranslationUnit_SkipFunctionBodies | CXTranslationUnit_KeepGoing,
		&translation_unit,
	)
	if error_code != 0 || translation_unit == nil {
		result.error_message = fmt.aprintf("libclang could not parse header '%s'", request.path, allocator=allocator)
		return result
	}
	defer api.dispose_translation_unit(translation_unit)

	for diagnostic_index in 0..<api.get_num_diagnostics(translation_unit) {
		diagnostic := api.get_diagnostic(translation_unit, diagnostic_index)
		severity := api.get_diagnostic_severity(diagnostic)
		if severity >= CXDiagnostic_Error && len(result.error_message) == 0 {
			result.error_message = clone_cx_string(&api, api.get_diagnostic_spelling(diagnostic), allocator)
		}
		api.dispose_diagnostic(diagnostic)
	}
	if len(result.error_message) > 0 {
		return result
	}

	ctx := Context{api=&api, result=&result, allocator=allocator}
	root := api.get_translation_unit_cursor(translation_unit)
	_ = api.visit_children(root, visit_cursor, &ctx)
	result.available = true
	return result
}