# Copyright 2022 Mattia Giambirtone & All Contributors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

## Utilities to print formatted error messages to stderr
import frontend/compiler/compiler
import frontend/parsing/parser
import frontend/parsing/lexer
import errors


import std/os
import std/terminal
import std/strutils
import std/strformat


proc printError(file, line: string, lineNo: int, pos: tuple[start, stop: int], fn: Declaration, msg: string) =
    ## Internal helper to print a formatted error message
    ## to stderr
    stderr.styledWrite(fgRed, styleBright, "Error in ", fgYellow, &"{file}:{lineNo}:{pos.start}")
    if not fn.isNil() and fn.kind == funDecl:
        stderr.styledWrite(fgRed, styleBright, " in function ", fgYellow, FunDecl(fn).name.token.lexeme)
    stderr.styledWriteLine(styleBright, fgDefault, ": ", msg)
    if line.len() > 0:
        stderr.styledWrite(fgRed, styleBright, "Source line: ", resetStyle, fgDefault, line[0..<pos.start])
        if pos.stop == line.len():
            stderr.styledWrite(fgRed, styleUnderscore, line[pos.start..<pos.stop])
            stderr.styledWriteLine(fgDefault, line[pos.stop..^1])
        else:
            stderr.styledWrite(fgRed, styleUnderscore, line[pos.start..pos.stop])
            stderr.styledWriteLine(fgDefault, line[pos.stop + 1..^1])


proc print*(exc: CompileError) =
    ## Prints a formatted error message 
    ## for compilation errors to stderr
    var file = exc.file
    var contents: string
    if file notin ["<string>", "", "stdin"]:
        file = relativePath(exc.file, getCurrentDir())
        contents = readFile(file).strip(chars={'\n'}).splitLines()[exc.line - 1]
    else:
        contents = exc.compiler.getSource().strip(chars={'\n'}).splitLines()[exc.line - 1]
    printError(file, contents, exc.line, exc.node.getRelativeBoundaries(), exc.function,
               exc.msg)


proc print*(exc: ParseError) =
    ## Prints a formatted error message 
    ## for parsing errors to stderr
    var file = exc.file
    if file notin ["<string>", ""]:
        file = relativePath(exc.file, getCurrentDir())
    printError(file, exc.parser.getSource().strip(chars={'\n'}).splitLines()[exc.line - 1], 
               exc.line, exc.token.relPos, exc.parser.getCurrentFunction(),
               exc.msg)


proc print*(exc: LexingError) =
    ## Prints a formatted error message 
    ## for lexing errors to stderr
    var file = exc.file
    if file notin ["<string>", ""]:
        file = relativePath(exc.file, getCurrentDir())
    printError(file, exc.lexer.getSource().strip(chars={'\n'}).splitLines()[exc.line - 1],
               exc.line, exc.pos, nil, exc.msg)