import os
import re
import sys

__all__ = ["Formatter"]

try:
    version = os.environ["VERSION_NUMBER"]
except KeyError:
    version = ""

styles = {
    "b": "\\fB@\\fR",
    "i": "\\fI@\\fR",
    "em": "\\fI@\\fR",
    "code": "\\fC@\\fR",
    "span": "\\fC@\\fR",
    "sup": "\\u@\\d",
    "hr": "",
}

formats = {
    "br": "\n.br\n",
    "h2": "\n.SH @",
    "h3": "\n.SS @",
    "h4": "\n.SS @",
    "dt": ('\n.IP "@" 4m', "no_nl"),
    "dd": "\n.br\n@",
    "ul": ("\n.RS 4n\n@\n.RE\n", "in_ul"),
    "menu": ("\n.RS 4n\n@\n.RE\n", "in_ul"),
    "dir": ("\n.RS 4n\n@\n.RE\n", "in_ul"),
    "ol": ("\n.IP\n@\n.PP\n", "index"),
    "p": "\n.PP\n@",
    "pre": ("\n.br\n.nf\n\\fC\n@\n\\fR\n.fi\n", "preformat"),
}

formats.update(styles)


def is_string(x):
    return isinstance(x, str)


def is_tuple(x):
    return isinstance(x, tuple)


def is_list(x):
    return isinstance(x, list)


def is_blank(s):
    return is_string(s) and s.strip() == ""


def clean(content):
    return [item for item in content if not is_blank(item)]


class Formatter:
    def __init__(self, filename, stream=sys.stdout):
        self.stream = stream
        self.style = {
            "preformat": False,
            "in_ul": False,
            "no_nl": False,
            "in_table": False,
            "in_tr": False,
            "index": [],
        }
        self.stack = []
        self.strip_re = re.compile(r"^[ \t]+")
        self.filename = filename
        self.at_bol = True

    def warning(self, msg):
        sys.stderr.write(msg + "\n")

    def set(self, var, val):
        self.style[var] = val

    def get(self, var):
        return self.style[var]

    def push(self, **kwargs):
        self.stack.append(self.style.copy())
        self.style.update(**kwargs)

    def pop(self):
        self.style = self.stack.pop()

    def show(self, s):
        self.stream.write(s)
        if s != "":
            self.at_bol = s.endswith("\n")

    def pp_with(self, content, var, val):
        self.push()
        self.set(var, val)
        self.pp(content)
        self.pop()

    def fmt(self, format, content, var=None):
        # String.partition is only in 2.5+
        # (pre,sep,post) = format.partition("@")
        if self.get("no_nl") and "\n" in format:
            self.warning("can't handle line breaks in <dt>...</dt>")
            format = "@"
        f = format.split("@", 1)
        pre = f[0]
        if len(f) > 1:
            sep = "@"
            post = f[1]
        else:
            sep = ""
            post = ""

        if pre != "":
            self.show(pre)
        if sep != "":
            if var:
                val = self.get("index") + [0] if var == "index" else True
                self.pp_with(content, var, val)
            else:
                self.pp(content)
        if post != "":
            self.show(post)

    def pp_li(self, content):
        if self.get("in_ul"):
            self.fmt("\n.IP \\(bu 4n\n@", content)
        else:
            idx = self.get("index")
            idx[-1] += 1
            sec = ".".join(map(str, idx))
            self.show("\n.IP \\fB%s\\fR\n" % sec)
            self.set("index", idx)
            self.pp(content)

    def pp_title(self):
        self.show(
            "\n.TH "
            + os.path.basename(self.filename).replace(".html", "")
            + ' 1 "" "GRASS '
            + version
            + '" "GRASS User\'s Manual"'
        )

    def pp_tr(self, content):
        content = clean(content)
        self.push(in_tr=True)
        col = 0
        for item in content:
            if not is_tuple(item):
                self.warning("invalid item in table row: %s" % str(item))
                continue
            (tag, attrs, body) = item
            if tag not in {"td", "th"}:
                self.warning("invalid tag in table row: %s" % tag)
                continue
            if col > 0:
                self.show("\t \t")
            self.show("T{\n")
            self.pp(body)
            self.show("\nT}")
            col += 1
        self.show("\n")
        self.pop()

    def pp_tbody(self, content):
        for item in content:
            if is_tuple(item):
                (tag, attrs, body) = item
                if tag in {"thead", "tbody", "tfoot"}:
                    self.pp_tbody(body)
                elif tag == "tr":
                    self.pp_tr(body)
                    self.show(".sp 1\n")

    def count_cols(self, content):
        cols = 0
        for item in content:
            n = 0
            if is_blank(item):
                pass
            elif is_tuple(item):
                (tag, attrs, body) = item
                if tag in {"thead", "tbody", "tfoot"}:
                    n = self.count_cols(body)
                elif tag == "tr":
                    n = len(clean(body))
                cols = max(cols, n)
            else:
                self.warning("invalid item in table: %s" % str(item))
        return cols

    def pp_table(self, content):
        cols = self.count_cols(content)
        if cols == 0:
            return
        self.show("\n.TS\nexpand;\n")
        self.show(" lw1 ".join(["lw60" for i in range(cols)]) + ".\n")
        self.pp_tbody(content)
        self.show("\n.TE\n")

    def pp_tag(self, tag, content):
        if self.get("in_tr") and tag not in styles:
            self.pp(content)
        elif tag in formats:
            spec = formats[tag]
            if is_string(spec):
                self.fmt(spec, content)
            else:
                (fmt, var) = spec
                self.fmt(fmt, content, var)
        elif tag == "table":
            if self.get("in_table"):
                self.warning("cannot handle nested tables")
                return
            self.push(in_table=True)
            self.pp_table(content)
            self.pop()
        elif tag == "li":
            self.pp_li(content)
        elif tag == "title":
            self.pp_title()
        else:
            self.pp(content)

    def pp_string(self, content):
        if content == "":
            return
        s = content
        if self.get("no_nl"):
            s = s.replace("\n", " ")
        s = s.replace("\\", "\\(rs")
        s = s.replace("'", "\\(cq")
        s = s.replace('"', "\\(dq")
        s = s.replace("`", "\\(ga")
        s = s.replace("-", "\\-")
        if self.at_bol and s[0] in {".", "'"}:
            s = "\\&" + s
        self.show(s)

    def pp_text(self, content):
        if content == "":
            return
        lines = content.splitlines(True)
        if len(lines) != 1:
            for line in lines:
                self.pp_text(line)
            return
        content = lines[0]
        if self.at_bol and not self.get("preformat"):
            content = self.strip_re.sub("", content)
        self.pp_string(content)

    def pp_list(self, content):
        for item in content:
            self.pp(item)

    def pp(self, content):
        if is_list(content):
            self.pp_list(content)
        elif is_tuple(content):
            (tag, attrs, body) = content
            self.pp_tag(tag, body)
        elif is_string(content):
            self.pp_text(content)
