""" Draw a parsed diff into a review view: the file text, coloured line regions, gutter marks, header phantom """
import html
import json
import logging
import os
from collections import namedtuple

import sublime
import sublime_plugin

from . import parse
from .git import STATUS_NAMES
from .state import VIEW_FLAG
from .utils import settings

LOG = logging.getLogger("vdiff")

KEY_DEL = "vdiff.del"
KEY_INS = "vdiff.ins"
KEY_DEL_GUTTER = "vdiff.del.gutter"
KEY_INS_GUTTER = "vdiff.ins.gutter"
KEY_DEL_CHAR = "vdiff.del.char"
KEY_INS_CHAR = "vdiff.ins.char"
REGION_KEYS = (KEY_DEL, KEY_INS, KEY_DEL_GUTTER, KEY_INS_GUTTER, KEY_DEL_CHAR, KEY_INS_CHAR)

PHANTOM_KEY = "vdiff.header"
STATUS_KEY = "vdiff"

# a block phantom anchored at point 0 is drawn below row 0, so row 0 stays empty and the file starts at row 1.
# Only index_point / caret_index know about it.
_HEADER_ROWS = 1

# scopes with a background in every bundled colour scheme (Mariana, Monokai, Breakers, Celeste, Sixteen)
SCOPE_DEL = "diff.deleted"
SCOPE_INS = "diff.inserted"
SCOPE_DEL_CHAR = "diff.deleted.char"
SCOPE_INS_CHAR = "diff.inserted.char"
# gutter dots use the scope's foreground
SCOPE_DEL_MARK = "markup.deleted"
SCOPE_INS_MARK = "markup.inserted"

# rules written into a colour-scheme override when the active scheme lacks the scopes above
FALLBACK_RULES = [
    {"scope": SCOPE_DEL, "background": "hsla(357, 45%, 60%, 0.15)", "foreground_adjust": "l(+ 5%)"},
    {"scope": SCOPE_DEL_CHAR, "background": "hsla(357, 60%, 60%, 0.30)", "foreground_adjust": "l(+ 10%)"},
    {"scope": SCOPE_INS, "background": "hsla(114, 31%, 68%, 0.15)", "foreground_adjust": "l(+ 5%)"},
    {"scope": SCOPE_INS_CHAR, "background": "hsla(114, 45%, 68%, 0.30)", "foreground_adjust": "l(+ 10%)"},
]

# one source for the status-bar hints and the ? popup.
# actions: the ACTIONS names the row covers; a single one makes the row a link. short: status-bar
# wording, "" keeps the row out of it. The group flag is False for groups needing a working-tree file.
Key = namedtuple("Key", "keys label short actions")

KEY_GROUPS = [
    ("Navigate", True, [
        Key("] [", "next / previous change", "change", ("next_change", "prev_change")),
        Key("n p", "next / previous file", "file", ("next_file", "prev_file")),
        Key("o \u23ce", "open the real file at this line", "open", ("open",)),
        Key("j k", "down / up one line (vim)", "", ("line_down", "line_up")),
    ]),
    ("Panels", True, [
        Key("f", "changed files", "files", ("files",)),
        Key("c", "recent commits", "commits", ("commits",)),
    ]),
    ("Actions", False, [
        Key("s", "stage", "stage", ("stage",)),
        Key("u", "unstage", "unstage", ("unstage",)),
        Key("d", "discard", "discard", ("discard",)),
        Key("C m", "commit the staged files", "commit", ("commit",)),
    ]),
    ("View", True, [
        Key("r", "refresh", "refresh", ("refresh",)),
        Key("?", "this list", "keys", ("help",)),
        Key("esc", "close the view", "", ("close",)),
    ]),
]

KEYS = [key for _, _, group in KEY_GROUPS for key in group]

KEY_HINTS = "   ".join("{} {}".format(k.keys, k.short) for k in KEYS if k.short)

# the popup font is the editor's, so the key column is padded to a fixed width in characters
_KEY_WIDTH = max(len(k.keys) for k in KEYS)

HEADER_CSS = """
body { margin: 0; padding: 0.5rem 0.8rem; background-color: color(var(--background) blend(var(--foreground) 93%)); }
.path { font-weight: bold; }
.old { color: color(var(--foreground) alpha(0.6)); }
.del { color: var(--redish); font-weight: bold; }
.ins { color: var(--greenish); font-weight: bold; }
.state { color: var(--orangish); }
.actions { margin-left: 1rem; }
.summary { margin-bottom: 0.3rem; color: color(var(--foreground) alpha(0.75)); }
.when { color: color(var(--foreground) alpha(0.6)); }
a { text-decoration: none; padding: 0.15rem 0.5rem; margin-left: 0.3rem; border-radius: 3px;
    background-color: color(var(--foreground) alpha(0.12)); color: var(--foreground); }
.danger { color: var(--redish); }
.hash { color: var(--bluish); font-weight: bold; }
.body { color: color(var(--foreground) alpha(0.6)); }
"""

# minihtml stops applying a stylesheet at the first selector it cannot parse, and its documentation
# covers properties only, not selectors: every rule here sticks to one bare element or one class,
# the forms HEADER_CSS proves work. The first group's margin stands in for body's top padding, and
# .kdim takes its colour from the .dim row around it.
HELP_CSS = """
body { margin: 0; padding: 0 0.8rem 0.6rem 0.8rem; }
.group { margin-top: 0.6rem; color: var(--bluish); font-weight: bold; }
.note { color: color(var(--foreground) alpha(0.5)); font-weight: normal; }
.row { color: color(var(--foreground) alpha(0.85)); }
.dim { color: color(var(--foreground) alpha(0.35)); }
.k { color: var(--orangish); font-weight: bold; }
.kdim { font-weight: bold; }
a { text-decoration: none; color: color(var(--foreground) alpha(0.85)); }
"""


class VdiffReplaceCommand(sublime_plugin.TextCommand):
    """Replace the whole buffer; the only writer of a review view"""

    def run(self, edit, text):
        self.view.replace(edit, sublime.Region(0, self.view.size()), text)


def init_view(view):
    """Settings a review view needs, applied once when it is created or restored"""
    s = view.settings()
    s.set(VIEW_FLAG, True)
    # native line numbers would be wrong: deleted lines have none
    s.set("line_numbers", False)
    s.set("word_wrap", False)
    s.set("gutter", True)
    s.set("highlight_line", True)
    s.set("scroll_past_end", False)
    s.set("detect_indentation", False)
    s.set("translate_tabs_to_spaces", False)
    s.set("show_definitions", False)
    s.set("mini_diff", False)
    s.set("spell_check", False)
    # a read-only viewer, so vim's insert mode is meaningless: open in command mode with the block
    # caret. vdiff's own keys carry no command_mode context, so they fire in either mode regardless.
    s.set("command_mode", True)
    s.set("inverse_caret_state", True)
    view.set_scratch(True)
    view.set_read_only(True)
    if not view.name():
        view.set_name("vDiff")
    view.set_status(STATUS_KEY, KEY_HINTS)
    ensure_scheme_scopes(view)


def index_point(view, index, col=0):
    """Text point of column `col` on the row showing st.lines[index]"""
    return view.text_point(index + _HEADER_ROWS, col)


def caret_index(view):
    """Index into st.lines of the caret's row (the header row maps to -1)"""
    if not len(view.sel()):
        return 0
    return view.rowcol(view.sel()[0].begin())[0] - _HEADER_ROWS


def fingerprint(st):
    """Cheap "did anything change" key for working-tree mode: mtimes of the file and of the git index"""
    if st.in_commit or st.change is None:
        return None
    return (_mtime(os.path.join(st.repo, st.change.path)), _mtime(os.path.join(st.repo, ".git", "index")))


def _mtime(path):
    try:
        return os.stat(path).st_mtime
    except OSError:
        return None


def render_message(view, st, message):
    """Show a one-line notice instead of a file (nothing to review, binary, ...)"""
    st.change = None
    st.lines = []
    st.blocks = []
    st.binary = False
    _replace(view, message)
    view.assign_syntax("scope:text.plain")
    _finish(view, st, 0, 0, "vDiff")


def render(view, st):
    """Draw st.lines for st.change into the view"""
    lines = st.lines
    if st.binary:
        text = "(binary file)"
    elif not lines:
        text = "(no textual changes)"
    else:
        text = "\n".join(line.text for line in lines)

    _replace(view, text)
    path = os.path.join(st.repo, st.change.path)
    _apply_syntax(view, path if lines and not st.binary else None)

    if lines and not st.binary:
        starts = _row_starts(lines)
        deleted, inserted = _line_regions(lines, starts)
        view.add_regions(KEY_DEL, deleted, SCOPE_DEL, flags=sublime.DRAW_NO_OUTLINE)
        view.add_regions(KEY_INS, inserted, SCOPE_INS, flags=sublime.DRAW_NO_OUTLINE)
        mark_flags = sublime.DRAW_NO_FILL | sublime.DRAW_NO_OUTLINE
        del_marks = [sublime.Region(starts[i]) for i, line in enumerate(lines) if line.kind == "-"]
        ins_marks = [sublime.Region(starts[i]) for i, line in enumerate(lines) if line.kind == "+"]
        view.add_regions(KEY_DEL_GUTTER, del_marks, SCOPE_DEL_MARK, icon="dot", flags=mark_flags)
        view.add_regions(KEY_INS_GUTTER, ins_marks, SCOPE_INS_MARK, icon="dot", flags=mark_flags)
        if settings().get("word_diff", True):
            del_chars, ins_chars = _char_regions(lines, st.blocks, starts)
            view.add_regions(KEY_DEL_CHAR, del_chars, SCOPE_DEL_CHAR, flags=sublime.DRAW_NO_OUTLINE)
            view.add_regions(KEY_INS_CHAR, ins_chars, SCOPE_INS_CHAR, flags=sublime.DRAW_NO_OUTLINE)

    ins, dele = parse.counts(lines)
    _finish(view, st, ins, dele, "⟐ {}".format(os.path.basename(st.change.path)))
    view.sel().clear()
    view.sel().add(sublime.Region(index_point(view, 0)))
    view.set_viewport_position((0, 0), False)


def _finish(view, st, ins, dele, name):
    """Header, tab name, status bar and bookkeeping shared by render and render_message"""
    _header(view, st, ins, dele)
    view.set_name(name)
    view.set_status(STATUS_KEY, KEY_HINTS)
    st.persist(view)
    st.fingerprint = fingerprint(st)


def _replace(view, text):
    view.set_read_only(False)
    try:
        view.run_command("vdiff_replace", {"text": "\n" * _HEADER_ROWS + text})
    finally:
        view.set_read_only(True)
    for key in REGION_KEYS:
        view.erase_regions(key)


def _apply_syntax(view, path):
    """The real file's syntax, so the diff is highlighted like the file itself"""
    syntax = None
    if path:
        try:
            syntax = sublime.find_syntax_for_file(path)
        except Exception:
            LOG.debug("find_syntax_for_file failed", exc_info=True)
    view.assign_syntax(syntax.path if syntax else "scope:text.plain")


def _row_starts(lines):
    """Text point where each line starts; computed from the text we wrote, no view round-trips"""
    starts = []
    point = _HEADER_ROWS
    for line in lines:
        starts.append(point)
        point += len(line.text) + 1
    starts.append(point - 1)  # end of the buffer (the last line has no newline)
    return starts


def _line_regions(lines, starts):
    """Full-line regions of deleted and inserted rows, consecutive rows merged"""
    regions = {"-": [], "+": []}
    for kind, start, end in parse.runs(lines, lambda line: line.kind):
        if kind in regions:
            # starts has a sentinel at len(lines): the last line stops at the buffer end
            regions[kind].append(sublime.Region(starts[start], starts[end]))
    return regions["-"], regions["+"]


def _char_regions(lines, blocks, starts):
    """Changed characters inside paired deleted/inserted lines"""
    deleted = []
    inserted = []
    for block in blocks:
        for del_row, ins_row in parse.paired_lines(lines, block):
            old_ranges, new_ranges = parse.char_ranges(lines[del_row].text, lines[ins_row].text)
            deleted.extend(sublime.Region(starts[del_row] + a, starts[del_row] + b) for a, b in old_ranges)
            inserted.extend(sublime.Region(starts[ins_row] + a, starts[ins_row] + b) for a, b in new_ranges)
    return deleted, inserted


def _summary_html(st):
    """Line above the header: the whole commit on one line, or how much of the tree is staged"""
    if not st.files and not st.commit:
        return ""
    if st.in_commit:
        text = " · ".join(_commit_parts(st))
    else:
        # staged means "has something staged": a partially staged file counts as staged only
        staged = sum(1 for c in st.files if c.staged)
        text = "{} staged, {} unstaged".format(staged, len(st.files) - staged)
    return '<div class="summary">{}</div>'.format(text)


def _commit_parts(st):
    """hash, author, date, totals and message — everything about the reviewed commit, in that order"""
    info = st.commit
    parts = []
    if info:
        parts.append('<span class="hash">{}</span>'.format(html.escape(info.short)))
        parts.append(html.escape(info.author))
        parts.append('<span class="when">{}</span>'.format(html.escape(info.date)))
    # binary files carry None counts but still changed, so they count toward the file total
    insertions = sum(c.insertions or 0 for c in st.files)
    deletions = sum(c.deletions or 0 for c in st.files)
    parts.append(
        '{} {} changed <span class="del">-{}</span> <span class="ins">+{}</span>'.format(
            len(st.files), "file" if len(st.files) == 1 else "files", deletions, insertions
        )
    )
    if info:
        message = html.escape(info.subject)
        body = info.body.strip().splitlines()
        if body:
            message += ' <span class="body">— {}</span>'.format(html.escape(body[0]))
        parts.append(message)
    return parts


def header_html(st, ins, dele):
    """The minihtml header: the summary line, then the shown file's path, counts, state and action links"""
    change = st.change
    if change is None:
        title = '<span class="path">vDiff</span>'
    else:
        title = '<span class="path">{}</span>'.format(html.escape(change.path))
        if change.old_path:
            title += ' <span class="old">← {}</span>'.format(html.escape(change.old_path))
        title += '&nbsp;&nbsp;<span class="del">-{}</span> <span class="ins">+{}</span>'.format(dele, ins)
        if not st.in_commit:
            state = "staged" if change.staged else STATUS_NAMES.get(change.status, "")
            if state:
                title += '&nbsp;&nbsp;<span class="state">{}</span>'.format(state)

    actions = []
    if change is not None and not st.in_commit:
        actions.append('<a href="stage">Stage</a>')
        actions.append('<a href="unstage">Unstage</a>')
        actions.append('<a href="discard" class="danger">Discard</a>')
    if change is not None:
        actions.append('<a href="open">Open</a>')
    actions.append('<a href="files">Files</a>')
    actions.append('<a href="commits">Commits</a>')
    actions.append('<a href="help" title="keys">?</a>')

    return '<body id="vdiff-header"><style>{}</style>{}<div>{}<span class="actions">{}</span></div></body>'.format(
        HEADER_CSS, _summary_html(st), title, "".join(actions)
    )


def _run_action(view, href):
    """Dispatch a header or popup link through the same command the keymap uses"""
    view.run_command("vdiff_action", {"action": href})


def _header(view, st, ins, dele):
    """One block phantom above the text; redrawn from scratch, so no PhantomSet state to keep"""

    def navigate(href):
        _run_action(view, href)

    view.erase_phantoms(PHANTOM_KEY)
    view.add_phantom(PHANTOM_KEY, sublime.Region(0), header_html(st, ins, dele), sublime.LAYOUT_BLOCK, navigate)


# --- key help popup ---------------------------------------------------------


def help_html(st):
    """The minihtml key list; rows that need a working-tree file are dimmed while a commit is shown"""
    parts = []
    for title, applies, group in KEY_GROUPS:
        dim = st.in_commit and not applies
        heading = html.escape(title)
        if dim:
            heading += ' <span class="note">uncommitted only</span>'
        parts.append('<div class="group">{}</div>'.format(heading))
        # one class per element: a compound selector would silently drop the rest of HELP_CSS
        row_class, key_class = ("dim", "kdim") if dim else ("row", "k")
        for key in group:
            row = '<span class="{}">{}</span>{}{}'.format(
                key_class, html.escape(key.keys), "&nbsp;" * (_KEY_WIDTH - len(key.keys) + 2), html.escape(key.label)
            )
            if len(key.actions) == 1 and not dim:
                row = '<a href="{}">{}</a>'.format(key.actions[0], row)
            parts.append('<div class="{}">{}</div>'.format(row_class, row))
    return '<body id="vdiff-help"><style>{}</style>{}</body>'.format(HELP_CSS, "".join(parts))


def show_help(view, st):
    """Toggle the key list popup at the caret"""
    if view.is_popup_visible():
        view.hide_popup()
        return

    def navigate(href):
        view.hide_popup()
        _run_action(view, href)

    # minihtml sizes follow the editor font, so fixed pixel bounds would clip at a large font size
    em = view.em_width() or 8
    view.show_popup(help_html(st), location=-1, max_width=int(em * 56), max_height=int(em * 44), on_navigate=navigate)


# --- colour scheme fallback -------------------------------------------------

_scheme_checked = set()


def ensure_scheme_scopes(view):
    """Write a scheme override with diff backgrounds when the active scheme has none (third-party schemes)"""
    name = _scheme_override_name(view)
    if not name or name in _scheme_checked:
        return
    _scheme_checked.add(name)
    try:
        if view.style_for_scope(SCOPE_INS).get("background"):
            return
    except Exception:
        return
    path = os.path.join(sublime.packages_path(), "User", name)
    try:
        scheme = {}
        if os.path.exists(path):
            with open(path, "r", encoding="utf-8") as f:
                scheme = sublime.decode_value(f.read()) or {}
        rules = scheme.setdefault("rules", [])
        present = {rule.get("scope") for rule in rules}
        rules.extend(rule for rule in FALLBACK_RULES if rule["scope"] not in present)
        with open(path, "w", encoding="utf-8") as f:
            json.dump(scheme, f, indent=4)
        LOG.info("wrote diff scopes into colour scheme override %s", path)
    except Exception:
        LOG.warning("could not write colour scheme override %s", path, exc_info=True)


def _scheme_override_name(view):
    """File name in Packages/User that overrides the active scheme (same base name, .sublime-color-scheme)"""
    try:
        # already resolved through "auto" and dark/light settings by sublime
        name = sublime.ui_info()["color_scheme"]["resolved_value"]
    except Exception:
        name = view.settings().get("color_scheme") or ""
    if not name or name == "auto":
        return None
    root, _ = os.path.splitext(os.path.basename(name))
    return root + ".sublime-color-scheme"