import { createElement } from 'react'
import type { Chapter } from '../../ui/types.ts'
import driver from '../onedim/driver.m?raw'
import fd2 from '../ch01/fd2.m?raw'
import richardson from './richardson.m?raw'
import text from './text.md?raw'
import { Convergence, fmtErr, type SweepOut } from '../onedim/panels.tsx'
import { KIND_CONTROL, NS_1D } from '../shared.ts'

export const ch02: Chapter = {
  id: 'limits',
  nav: 'Second order to its limit',
  part: 'One dimension',
  title: 'Second order, to its limit',
  blurb: 'Conditioning, the roundoff floor at about eight digits, and Richardson extrapolation.',
  text,
  labs: [
    {
      id: 'floor',
      title: 'Refining until it stops helping',
      caption:
        'Nine resolutions from 16 to 262144 intervals. The last few take a second or two each; the whole sweep runs on request.',
      driver,
      script: fd2,
      manual: true,
      controls: [
        KIND_CONTROL,
        {
          kind: 'slider',
          key: 'nmax',
          label: 'finest N',
          values: [16384, 65536, 262144, 1048576],
          min: 0,
          max: 3,
          format: (v) => String(v),
        },
      ],
      defaults: { kind: 'smooth', mode: 'sweep', ns: [], nmax: 262144, nmaxs: [1e9], timed: 1 },
      derive: (p) => ({
        ...p,
        ns: [16, 64, 256, 1024, 4096, 16384, 65536, 262144, 1048576].filter((n) => n <= Number(p.nmax)),
      }),
      render: (d: SweepOut) =>
        createElement(Convergence, {
          data: d,
          style: {
            slots: ['fd2'],
            refs: [
              { p: -2, label: 'slope −2: discretisation' },
              { p: 2, label: 'slope +2: roundoff × κ(A)', at: [1e3, 2e-13] },
            ],
          },
          height: 340,
        }),
      summary: (d: SweepOut) => {
        const es = d.E[0]
        let bi = 0
        es.forEach((v, i) => {
          if (v != null && (es[bi] == null || v < (es[bi] as number))) bi = i
        })
        return [
          { label: 'best error', value: fmtErr(es[bi]) },
          { label: 'at N', value: String(d.ns[bi]) },
        ]
      },
    },
    {
      id: 'richardson',
      title: 'Two second-order solves, one fourth-order answer',
      caption: 'Change the manufactured solution to lowreg and watch the gain evaporate.',
      driver,
      script: richardson,
      editorOpen: true,
      controls: [KIND_CONTROL],
      defaults: { kind: 'smooth', mode: 'sweep', ns: NS_1D, nmaxs: [1e9, 1e9], timed: 0 },
      render: (d: SweepOut) =>
        createElement(Convergence, {
          data: d,
          style: {
            slots: ['fd2', 'fd4'],
            refs: [
              { p: -2, label: 'slope −2' },
              { p: -4, label: 'slope −4' },
            ],
          },
        }),
      summary: (d: SweepOut) => {
        const q = d.orders[1]?.[d.orders[1].length - 1]
        return [
          { label: 'extrapolated error', value: fmtErr(d.E[1]?.[d.E[1].length - 1]) },
          { label: 'observed order', value: q == null ? '--' : q.toFixed(2) },
        ]
      },
    },
  ],
}