import { SUBSYSTEMS, type CarCondition } from '../sim/car';
import type { HeatLevel } from '../sim/heat';
import { MISSION_SHAPE, type MissionType } from '../sim/quests';
import type { Control } from '../sim/regions';


const BAR_WIDTH = 12;

/**
 * Draws a bar with a notch for the ceiling: the fillable part is what repairs
 * can still reach, and the gap past it is gone for good.
 */
function bar(value: number, ceiling = 1): string {
  const filled = Math.round(value * BAR_WIDTH);
  const reachable = Math.round(ceiling * BAR_WIDTH);
  return (
    '█'.repeat(filled) + '·'.repeat(Math.max(0, reachable - filled)) + '×'.repeat(BAR_WIDTH - reachable)
  );
}

export interface HudModel {
  heat: {
    segmentId: number | null;
    /** False while on the verge — still counts as using the road. */
    onTarmac: boolean;
    value: number;
    /** Standing of the district, which feeds every road through it. */
    area: number;
    level: HeatLevel | null;
  };
  quest: {
    type: MissionType;
    stage: 'travel' | 'working' | 'return';
    novel: boolean;
    worked: number;
    cargo: number;
    distance: number;
    /** Radians from the car's nose to the target, positive to the left. */
    bearing: number;
  } | null;
  control: Control;
  pursuit: {
    /** 0..1 toward being recognised. */
    meter: number;
    alert: 'clear' | 'suspicious' | 'hunted';
    hunters: number;
    /** Seconds of staying out of sight before they give up. */
    losingIn: number;
  };
  /** Rounds in the air nearby. Not a health bar — a reason to keep moving. */
  danger: number;
  completed: number;
  /** Jobs dropped or lost with a car. */
  failed: number;
  /** Cars written off underneath the player. */
  kia: number;
  parts: number;
  notice: string;
  /** 0..1 toward wiping the campaign, while R is held. */
  resetProgress: number;
  muted: boolean;
}

/** Eight-point compass, starting at "straight ahead" and turning left. */
const ARROWS = ['↑', '↖', '←', '↙', '↓', '↘', '→', '↗'];

const arrowFor = (bearing: number): string => {
  const sector = Math.round(bearing / (Math.PI / 4));
  return ARROWS[((sector % 8) + 8) % 8]!;
};

/**
 * The one meter the player is meant to watch. Deliberately not a number: it is
 * "how close am I to being made", and it wants reading at a glance while
 * driving.
 */
function pursuitLines(pursuit: HudModel['pursuit']): string[] {
  if (pursuit.alert === 'hunted') {
    return [
      `HUNTED — ${pursuit.hunters} on you`,
      pursuit.losingIn > 0
        ? `break line of sight · ${pursuit.losingIn.toFixed(0)}s to lose them`
        : 'they can see you',
    ];
  }
  if (pursuit.meter <= 0.02) return ['cover intact'];
  return [`noticed ${bar(pursuit.meter)}${pursuit.alert === 'suspicious' ? ' — being watched' : ''}`];
}

const CONTROL_WORDS: Record<Control, string> = {
  liberated: 'liberated — nobody is watching the roads here',
  contested: 'contested — the roads remember, slowly',
  occupied: 'occupied — every road you use is noticed',
  frontier: 'frontier — beyond the line, and it shows',
};

function questLines(quest: NonNullable<HudModel['quest']>): string[] {
  const shape = MISSION_SHAPE[quest.type];
  const label = shape.label;
  const kind = quest.novel ? 'new target' : 'known target';
  if (quest.stage === 'return') {
    // Only retrieval has anything aboard that can be spoiled on the way home.
    const cargo = shape.cargoHome ? ` · cargo ${(quest.cargo * 100).toFixed(0)}%` : '';
    return [`${label} done — return to any base${cargo}`];
  }
  if (quest.stage === 'working') {
    return [`${label} — ${shape.working} ${quest.worked.toFixed(1)}/${shape.work}s (hold still)`];
  }
  return [
    `${label} (${kind})`,
    `${arrowFor(quest.bearing)}  ${(quest.distance / 1000).toFixed(2)} km to target`,
  ];
}

/**
 * @param debug Show the scaffolding: heat values, the district's standing, the
 *   road you are on, and the name of the band you are in.
 *
 *   These exist to tune curves, and every one of them actively works against
 *   the thing it is measuring. Phase 3's gate is telling occupied ground from
 *   liberated *without being told*, and there was a line on screen naming it.
 *   Phase 1's gate is avoiding a road because of its history, with a numeric
 *   heat meter sitting underneath it. You cannot judge either while reading the
 *   answer, so they live behind `?debug` and the world has to speak for itself.
 */
export function createHud(seed: number, debug = false) {
  const el = document.getElementById('hud')!;
  let last = 0;

  return {
    update(speedMs: number, condition: CarCondition, now: number, model: HudModel) {
      // Text at 10 Hz. Nothing here changes fast enough to want a frame each.
      if (now - last < 0.1) return;
      last = now;

      const lines = [
        `${Math.abs(speedMs * 3.6).toFixed(0).padStart(3)} km/h`,
        '',
        ...SUBSYSTEMS.map(
          (part) =>
            `${part.padEnd(7)} ${bar(condition.level[part], condition.ceiling[part])} ` +
            `${(condition.level[part] * 100).toFixed(0)}%`,
        ),
        `parts   ${model.parts.toFixed(2)}   runs ${model.completed}` +
          (model.failed > 0 ? `   lost ${model.failed}` : '') +
          // Cars are counted, not lives. There is no stock of them to run out
          // of; the number is there so a long campaign reads as a history.
          (model.kia > 0 ? `   cars ${model.kia + 1}` : ''),
        '',
        ...(model.quest ? questLines(model.quest) : ['no mission — find a base']),
        '',
        // Which band you are in is meant to be read off the light, the fog and
        // who is standing in the street. Naming it hands over the answer.
        ...(debug ? [CONTROL_WORDS[model.control]] : []),
        ...pursuitLines(model.pursuit),
        ...(model.danger > 0 ? [`⚠ rounds in the air nearby (${model.danger})`] : []),
        '',
        // Heat is meant to be read off what is physically sitting in the road,
        // so the meter that exists to tune it cannot also be on screen.
        ...(debug
          ? [
              `[debug] road ${
                model.heat.segmentId === null
                  ? 'off-route'
                  : `#${model.heat.segmentId} ${model.heat.onTarmac ? '(on road)' : '(alongside)'}`
              }`,
              `[debug] heat ${bar(model.heat.value)} ${model.heat.level ?? '—'}`,
              `[debug] area ${bar(model.heat.area)}`,
              '',
              `[debug] seed ${seed}`,
            ]
          : []),
        'WASD drive · space handbrake · R respawn',
        `at a base: X drop job · C overhaul` + ` · M sound ${model.muted ? 'off' : 'on'}`,
        'hold R to reset the campaign',
      ];
      if (model.resetProgress > 0.06) {
        lines.push('', `RESETTING ${bar(Math.min(1, model.resetProgress))} keep holding R`);
      }
      if (model.notice) lines.push('', `» ${model.notice}`);
      el.textContent = lines.join('\n');
    },
  };
}