import io
import logging
import textwrap
from collections import namedtuple

import flask
import lxml.etree as xmltree
import mermaid

from . import core, gamedata

pth_upgrade_schema = core.path_appdir / "basepak/rules/schemas/upgrades.xsd"
doc_upgrade_schema = xmltree.parse(pth_upgrade_schema.as_posix())
upgrade_schema = xmltree.XMLSchema(doc_upgrade_schema)
upgrade_schema_parser = xmltree.XMLParser(schema=upgrade_schema)

UpgradeData = namedtuple("UpgradeData", ["id", "name", "desc", "requires"])

## \brief Renders an upgrade tree.
#  \param tree The upgrade tree to retrieve.
#  \api{GET} /upgrades/`<tree>`
#  \return An SVG.
@core.app.route("/upgrades/<tree>")
def get_upgrade_tree(tree):
    buf_mmd = io.StringIO()
    rulefile = xmltree.parse(gamedata.vfs.open(f"/rules/upgrades/{tree}.xml"), upgrade_schema_parser)
    ruleset = rulefile.getroot()

    hnd_treedata = ruleset.xpath("./upgrades:TreeData", namespaces=core.xml_namespaces)[0]
    hnd_name = hnd_treedata.xpath("./upgrades:Name", namespaces=core.xml_namespaces)[0]
    hnd_primary_color = hnd_treedata.xpath("./upgrades:PrimaryColor", namespaces=core.xml_namespaces)[0]

    buf_mmd.write(textwrap.dedent(f"""
    ----
    title: {hnd_name.text}
    theme: base
    themeVariables:
        primaryColor: {hnd_primary_color.text}
    ----
    flowchart LR
    """))

    tree_upgrades = []
    for hnd_upgrade in ruleset.iter("{seagull:rules/upgrades}Upgrade"):
        hnd_id = hnd_upgrade.xpath("./upgrades:Id", namespaces=core.xml_namespaces)[0]
        hnd_upgrade_name = hnd_upgrade.xpath("./upgrades:Name", namespaces=core.xml_namespaces)[0]
        hnd_desc = hnd_upgrade.xpath("./upgrades:Desc", namespaces=core.xml_namespaces)[0]
        try:
            hnd_requires = hnd_upgrade.xpath("./upgrades:Requirements", namespaces=core.xml_namespaces)[0]
            require_list = [elem.text for elem in hnd_requires.iter("{seagull:rules/upgrades}Require")]
        except IndexError:
            require_list = []

        upgrade = UpgradeData(
            id=hnd_id.text,
            name=hnd_upgrade_name.text,
            desc=hnd_desc.text,
            requires=require_list
        )

        tree_upgrades.append(upgrade)
    
    tiers = {}
    dependency_lines = []
    for upgrade in tree_upgrades:
        deptier = 0
        buf_mmd.write(f"    {upgrade.id}@{{label: \"{upgrade.name}\"}}\n")
        collected_tiers = []
        for require in upgrade.requires:
            if require in tiers:
                collected_tiers.append(tiers[require])
            
            dependency_lines.append(f"    {require} --> {upgrade.id}\n")
        
        if len(collected_tiers) > 0:
            deptier = max(collected_tiers)
        
        tiers[upgrade.id] = deptier + 1
    
    for line in dependency_lines:
        buf_mmd.write(line)

    buf_mmd.seek(0)
    print(buf_mmd.read())
    return get_upgrade_tree_mmd(tree) # TEMP

def get_upgrade_tree_mmd(tree):
    if not gamedata.vfs.exists(f"upgrades/{tree}.mmd"):
        return flask.make_response("No Upgrade Tree", 404)
    
    with gamedata.vfs.open(f"upgrades/{tree}.mmd") as fd_upgradetree:
        mmd_upgradetree = mermaid.Mermaid(fd_upgradetree.read(), height=400)
        return mmd_upgradetree.svg_response.content