import { useState } from 'react';
import type { Campaign, Character, Combatant, Encounter } from '@/lib/schemas';
import { encountersRepo } from '@/lib/db/repositories';
import { newId } from '@/lib/ids';
import { createRng } from '@/lib/rng';
import { rollDice } from '@/lib/dice/notation';
import { getSystem } from '@/lib/rules';
import { useCharacters } from '@/features/characters/hooks';
import {
  addCombatant,
  applyDamage,
  applyHealing,
  currentCombatant,
  endEncounter,
  moveCombatant,
  nextTurn,
  previousTurn,
  removeCombatant,
  startEncounter,
  updateCombatant,
} from '@/lib/combat/engine';
import { Button } from '@/components/ui/Button';
import { Input, Select } from '@/components/ui/Input';
import { NumberField } from '@/components/ui/NumberField';

export function EncounterTracker({ encounter, campaign }: { encounter: Encounter; campaign: Campaign }) {
  const characters = useCharacters(campaign.id);

  const mutate = (fn: (e: Encounter) => Encounter) => {
    void encountersRepo.save(fn(encounter));
  };

  const current = currentCombatant(encounter);
  const isActive = encounter.status === 'active';

  return (
    <div>
      {/* Control bar */}
      <div className="mb-4 flex flex-wrap items-center gap-3 rounded-lg border border-line bg-panel p-3">
        <div>
          <div className="font-display text-lg font-semibold text-ink">{encounter.name}</div>
          <div className="text-xs text-muted">
            {isActive ? `Round ${encounter.round}` : encounter.status === 'ended' ? 'Ended' : 'Not started'}
            {current && isActive ? ` · ${current.name}'s turn` : ''}
          </div>
        </div>
        <div className="ml-auto flex gap-2">
          {!isActive && encounter.status !== 'ended' && (
            <Button
              variant="primary"
              disabled={encounter.combatants.length === 0}
              onClick={() => mutate(startEncounter)}
            >
              Start combat
            </Button>
          )}
          {isActive && (
            <>
              <Button variant="secondary" onClick={() => mutate(previousTurn)}>
                ← Prev
              </Button>
              <Button variant="primary" onClick={() => mutate(nextTurn)}>
                Next turn →
              </Button>
              <Button variant="ghost" className="text-danger" onClick={() => mutate(endEncounter)}>
                End
              </Button>
            </>
          )}
          {encounter.status === 'ended' && (
            <Button variant="secondary" onClick={() => mutate((e) => ({ ...e, status: 'planning', round: 0, turnIndex: 0 }))}>
              Reopen
            </Button>
          )}
        </div>
      </div>

      <AddCombatantBar encounter={encounter} characters={characters} onAdd={(c) => mutate((e) => addCombatant(e, c))} />

      {/* Combatant list */}
      {encounter.combatants.length === 0 ? (
        <p className="mt-6 text-sm text-muted">No combatants yet. Add characters or monsters above.</p>
      ) : (
        <ul className="mt-4 space-y-2">
          {encounter.combatants.map((c, idx) => (
            <CombatantRow
              key={c.id}
              combatant={c}
              isCurrent={isActive && idx === encounter.turnIndex}
              onChange={(patch) => mutate((e) => updateCombatant(e, c.id, patch))}
              onDamage={(amt) => mutate((e) => updateCombatant(e, c.id, { hp: applyDamage(c, amt).hp }))}
              onHeal={(amt) => mutate((e) => updateCombatant(e, c.id, { hp: applyHealing(c, amt).hp }))}
              onMove={(dir) => mutate((e) => moveCombatant(e, c.id, dir))}
              onRemove={() => mutate((e) => removeCombatant(e, c.id))}
            />
          ))}
        </ul>
      )}
    </div>
  );
}

function rollInitiativeFor(character: Character | undefined): number {
  if (!character) return rollDice('1d20', createRng()).total;
  const mod = getSystem(character.system).initiativeModifier({
    level: character.level,
    abilities: character.abilities,
    perceptionRank: character.perceptionRank,
  });
  return rollDice('1d20', createRng()).total + mod;
}

function AddCombatantBar({
  characters,
  onAdd,
}: {
  encounter: Encounter;
  characters: Character[];
  onAdd: (c: Combatant) => void;
}) {
  const [name, setName] = useState('');
  const [init, setInit] = useState(10);
  const [ac, setAc] = useState(12);
  const [hp, setHp] = useState(10);

  const addCustom = () => {
    if (name.trim() === '') return;
    onAdd({
      id: newId(),
      name: name.trim(),
      kind: 'monster',
      initiative: init,
      ac,
      hp: { current: hp, max: hp, temp: 0 },
      conditions: [],
      notes: '',
    });
    setName('');
  };

  const addCharacter = (charId: string) => {
    const ch = characters.find((c) => c.id === charId);
    if (!ch) return;
    const sys = getSystem(ch.system);
    onAdd({
      id: newId(),
      name: ch.name,
      kind: ch.kind,
      characterId: ch.id,
      initiative: rollInitiativeFor(ch),
      ac: sys.baseArmorClass({ level: ch.level, abilities: ch.abilities, armorBonus: ch.armorBonus }),
      hp: { ...ch.hp },
      conditions: [],
      notes: '',
    });
  };

  return (
    <div className="space-y-2 rounded-lg border border-line bg-panel/60 p-3">
      <div className="flex flex-wrap items-end gap-2">
        <label className="flex-1 min-w-40 text-xs text-muted">
          Name
          <Input value={name} onChange={(e) => setName(e.target.value)} placeholder="Goblin Boss" onKeyDown={(e) => e.key === 'Enter' && addCustom()} />
        </label>
        <label className="text-xs text-muted">
          Init
          <NumberField className="w-16" value={init} onChange={setInit} aria-label="Initiative" />
        </label>
        <label className="text-xs text-muted">
          AC
          <NumberField className="w-16" value={ac} min={0} onChange={setAc} aria-label="Armor class" />
        </label>
        <label className="text-xs text-muted">
          HP
          <NumberField className="w-20" value={hp} min={0} onChange={setHp} aria-label="Hit points" />
        </label>
        <Button variant="primary" onClick={addCustom}>
          Add
        </Button>
      </div>
      {characters.length > 0 && (
        <div className="flex items-center gap-2">
          <span className="text-xs text-muted">Add character (rolls initiative):</span>
          <Select
            className="w-auto"
            value=""
            onChange={(e) => {
              if (e.target.value) addCharacter(e.target.value);
              e.target.value = '';
            }}
          >
            <option value="">Choose…</option>
            {characters.map((c) => (
              <option key={c.id} value={c.id}>
                {c.name} (Lv {c.level})
              </option>
            ))}
          </Select>
        </div>
      )}
    </div>
  );
}

function CombatantRow({
  combatant: c,
  isCurrent,
  onChange,
  onDamage,
  onHeal,
  onMove,
  onRemove,
}: {
  combatant: Combatant;
  isCurrent: boolean;
  onChange: (patch: Partial<Combatant>) => void;
  onDamage: (amt: number) => void;
  onHeal: (amt: number) => void;
  onMove: (dir: -1 | 1) => void;
  onRemove: () => void;
}) {
  const [delta, setDelta] = useState(0);
  const [conditionText, setConditionText] = useState('');
  const dead = c.hp.current <= 0;

  return (
    <li
      className={
        'rounded-lg border bg-panel p-3 ' +
        (isCurrent ? 'border-accent ring-1 ring-accent/40' : 'border-line') +
        (dead ? ' opacity-60' : '')
      }
    >
      <div className="flex flex-wrap items-center gap-3">
        <div className="flex flex-col items-center">
          <NumberField className="w-14" value={c.initiative} onChange={(initiative) => onChange({ initiative })} aria-label={`${c.name} initiative`} />
          <span className="mt-0.5 text-[10px] uppercase text-muted">init</span>
        </div>

        <div className="min-w-32 flex-1">
          <div className="flex items-center gap-2">
            <span className="font-medium text-ink">{c.name}</span>
            <span className="rounded bg-elevated px-1.5 text-[10px] uppercase text-muted">{c.kind}</span>
            {dead && <span className="text-xs font-semibold text-danger">DOWN</span>}
          </div>
          {c.conditions.length > 0 && (
            <div className="mt-1 flex flex-wrap gap-1">
              {c.conditions.map((cond, i) => (
                <button
                  key={`${cond.name}-${i}`}
                  className="rounded-full bg-warning/15 px-2 py-0.5 text-xs text-warning hover:line-through"
                  title="Click to remove"
                  onClick={() => onChange({ conditions: c.conditions.filter((_, j) => j !== i) })}
                >
                  {cond.name}
                  {cond.value ? ` ${cond.value}` : ''} ✕
                </button>
              ))}
            </div>
          )}
        </div>

        {/* HP */}
        <div className="text-center">
          <div className="text-sm">
            <span className={dead ? 'text-danger' : 'text-ink'}>{c.hp.current}</span>
            <span className="text-muted">/{c.hp.max}</span>
            {c.hp.temp > 0 && <span className="text-info"> +{c.hp.temp}</span>}
          </div>
          <div className="mt-1 flex items-center gap-1">
            <NumberField className="w-14" value={delta} min={0} onChange={setDelta} aria-label={`${c.name} HP amount`} />
            <Button size="sm" variant="danger" disabled={delta <= 0} onClick={() => { onDamage(delta); setDelta(0); }} title="Apply damage">
              Dmg
            </Button>
            <Button size="sm" variant="secondary" disabled={delta <= 0} onClick={() => { onHeal(delta); setDelta(0); }} title="Heal">
              Heal
            </Button>
          </div>
        </div>

        <div className="text-center text-sm">
          <div className="text-muted">AC</div>
          <NumberField className="w-12" value={c.ac} min={0} onChange={(ac) => onChange({ ac })} aria-label={`${c.name} AC`} />
        </div>

        <div className="flex flex-col gap-1">
          <Button size="icon" variant="ghost" onClick={() => onMove(-1)} aria-label="Move up" title="Move up">↑</Button>
          <Button size="icon" variant="ghost" onClick={() => onMove(1)} aria-label="Move down" title="Move down">↓</Button>
        </div>
        <Button size="icon" variant="ghost" className="text-danger" onClick={onRemove} aria-label={`Remove ${c.name}`}>✕</Button>
      </div>

      <div className="mt-2 flex items-center gap-2">
        <Input
          className="h-8 max-w-48 text-xs"
          value={conditionText}
          placeholder="Add condition (e.g. Prone, Frightened 2)"
          onChange={(e) => setConditionText(e.target.value)}
          onKeyDown={(e) => {
            if (e.key === 'Enter' && conditionText.trim()) {
              const m = /^(.*?)(?:\s+(\d+))?$/.exec(conditionText.trim());
              const nameOnly = (m?.[1] ?? conditionText).trim();
              const value = m?.[2] ? Number(m[2]) : undefined;
              onChange({ conditions: [...c.conditions, { name: nameOnly, ...(value ? { value } : {}) }] });
              setConditionText('');
            }
          }}
        />
      </div>
    </li>
  );
}