import { createElement, Fragment } from 'react'
import type { Chapter } from '../../ui/types.ts'
import driver from '../twodim/driver.m?raw'
import script from './fastpoisson.m?raw'
import text from './text.md?raw'
import { Convergence, WorkPrecision, fmtErr, type SweepOut } from '../onedim/panels.tsx'
import { EXACT2D_CONTROL } from '../shared.ts'
import type { MethodKey } from '../../plot/palette.ts'

const SLOTS: MethodKey[] = ['fd2', 'fast']

export const ch06: Chapter = {
  id: 'fast-poisson',
  nav: 'The fast Poisson solver',
  part: 'Two dimensions',
  title: 'The fast Poisson solver',
  blurb: 'The same discretisation, diagonalised by the sine transform: a million unknowns in half a second.',
  text,
  labs: [
    {
      id: 'compare',
      title: 'Elimination against the sine transform',
      caption:
        'Both curves are the same discretisation, so where they overlap they lie exactly on top of each other; the sine transform is drawn dashed so that the dense solve shows through. The dense solve stops at N = 32 because that is where it stops being possible.',
      driver,
      script,
      manual: true,
      editorOpen: true,
      controls: [
        EXACT2D_CONTROL,
        {
          kind: 'slider',
          key: 'nmax',
          label: 'finest N for the fast solver',
          values: [128, 256, 512, 1024, 2048],
          min: 0,
          max: 4,
          format: (v) => String(v),
        },
      ],
      defaults: {
        kind: 'expsin',
        par: 1,
        mode: 'sweep',
        ns: [],
        nmax: 512,
        nmaxs: [32, 512],
        timed: 1,
      },
      derive: (p) => ({
        ...p,
        ns: [8, 16, 32, 64, 128, 256, 512, 1024, 2048].filter((n) => n <= Number(p.nmax)),
        nmaxs: [32, Number(p.nmax)],
      }),
      render: (d: SweepOut) =>
        createElement(
          Fragment,
          null,
          createElement(Convergence, {
            key: 'c',
            data: d,
            style: { slots: SLOTS, dashes: [undefined, '7 5'], refs: [{ p: -2, label: 'slope −2' }] },
          }),
          createElement(WorkPrecision, { key: 'w', data: d, style: { slots: SLOTS, dashes: [undefined, '7 5'] } }),
        ),
      summary: (d: SweepOut) => {
        const last = d.E[1].length - 1
        return [
          { label: 'finest error', value: fmtErr(d.E[1][last]) },
          { label: 'in', value: `${(d.T[1][last] ?? 0).toFixed(0)} ms` },
        ]
      },
    },
  ],
}