import { FORBIDDEN_COLOR_RE } from '@/lib/interactive-demo/constants'
import { validateInteractiveDemo } from '@/lib/interactive-demo/validate'
import { getPlugin } from '@/lib/simulators'
import {
  INTERACTIVE_PAGE_CAPS,
  isPageHumanStringKey,
} from './constants'
import { pageSpecV1Schema } from './schema'
import { validateSimExprRefs } from './sim-eval'
import type {
  PageBlock,
  PageSpecV1,
  PageValidationIssue,
  PageValidationResult,
} from './types'

function issue(code: string, path: string, message: string): PageValidationIssue {
  return { code, path, message }
}

function scanForbiddenColors(
  value: unknown,
  path: string,
  out: PageValidationIssue[]
): void {
  if (typeof value === 'string') {
    if (FORBIDDEN_COLOR_RE.test(value)) {
      out.push(
        issue(
          'forbidden_color',
          path,
          'Free color literals (hex/rgb) are forbidden — use intent enums'
        )
      )
    }
    return
  }
  if (Array.isArray(value)) {
    value.forEach((v, i) => scanForbiddenColors(v, `${path}[${i}]`, out))
    return
  }
  if (value && typeof value === 'object') {
    for (const [k, v] of Object.entries(value)) {
      if (isPageHumanStringKey(k)) continue
      // Nested demos are validated separately (incl. their own color scan)
      if (k === 'demo') continue
      scanForbiddenColors(v, path ? `${path}.${k}` : k, out)
    }
  }
}

function countDemos(page: PageSpecV1): number {
  let n = 0
  for (const s of page.sections) {
    for (const b of s.blocks) {
      if (b.type === 'demo') n += 1
    }
  }
  return n
}

function countSims(page: PageSpecV1): number {
  let n = 0
  for (const s of page.sections) {
    for (const b of s.blocks) {
      if (b.type === 'sim') n += 1
    }
  }
  return n
}

/** Simulator block: catalog ref integrity / generic exprs safety. */
function validateSim(
  block: Extract<PageBlock, { type: 'sim' }>,
  path: string,
  out: PageValidationIssue[]
): void {
  const sim = block.sim
  if (sim.simId === 'generic-formula') {
    const generic = sim as Extract<typeof sim, { simId: 'generic-formula' }>
    const paramIds = new Set(generic.params.map((p) => p.id))
    for (const p of generic.params) {
      if (p.min >= p.max) {
        out.push(issue('sim_param_range', `${path}.params`, `Param "${p.id}": min >= max`))
      }
      if (p.defaultValue < p.min || p.defaultValue > p.max) {
        out.push(
          issue('sim_param_default', `${path}.params`, `Param "${p.id}": default outside [min, max]`)
        )
      }
    }
    const allowed = new Set<string>(paramIds)
    for (const c of generic.computed) {
      const errs = validateSimExprRefs(c.expr, allowed)
      for (const e of errs) {
        out.push(issue('sim_expr', `${path}.computed.${c.id}`, e))
      }
      if (errs.length === 0) allowed.add(c.id) // computed may chain
    }
    if (generic.visual.kind === 'curve') {
      if (!paramIds.has(generic.visual.xParamId)) {
        out.push(
          issue('sim_curve_param', `${path}.visual.xParamId`, `Unknown param "${generic.visual.xParamId}"`)
        )
      }
      const errs = validateSimExprRefs(generic.visual.expr, allowed)
      for (const e of errs) {
        out.push(issue('sim_expr', `${path}.visual.expr`, e))
      }
    }
    return
  }

  // Catalog plugin: must exist. Sims: preset within bounds + compute finite.
  const catalog = sim as Extract<typeof sim, { simId: string }> & {
    preset?: Record<string, number>
  }
  const plugin = getPlugin(catalog.simId)
  if (!plugin) {
    out.push(issue('unknown_simulator', `${path}.simId`, `Unknown simulator "${catalog.simId}"`))
    return
  }
  if (plugin.family === 'anim') {
    if (!plugin.beats.length) {
      out.push(issue('sim_anim_empty', `${path}`, 'Animation plugin has no beats'))
    }
    return
  }
  const env: Record<string, number> = {}
  for (const p of plugin.params) env[p.id] = p.defaultValue
  if (catalog.preset) {
    for (const [k, v] of Object.entries(catalog.preset)) {
      const def = plugin.params.find((p) => p.id === k)
      if (!def) {
        out.push(issue('sim_preset_key', `${path}.preset.${k}`, 'Not a parameter of this simulator'))
        continue
      }
      if (v < def.min || v > def.max) {
        out.push(
          issue('sim_preset_range', `${path}.preset.${k}`, `Value ${v} outside [${def.min}, ${def.max}]`)
        )
        continue
      }
      env[k] = v
    }
  }
  try {
    const result = plugin.compute(env)
    for (const o of plugin.outputs) {
      if (!Number.isFinite(result[o.id])) {
        out.push(
          issue('sim_compute', `${path}`, `Output "${o.id}" not finite at preset values`)
        )
      }
    }
  } catch {
    out.push(issue('sim_compute', `${path}`, 'Simulator compute() threw at preset values'))
  }
}

function validateTable(
  block: Extract<PageBlock, { type: 'table' }>,
  path: string,
  out: PageValidationIssue[]
): void {
  const cols = block.columns.length
  for (const [ri, row] of block.rows.entries()) {
    if (row.length !== cols) {
      out.push(
        issue(
          'table_shape',
          `${path}.rows[${ri}]`,
          `Expected ${cols} cells, got ${row.length}`
        )
      )
    }
  }
}

function validateImageSrc(
  block: Extract<PageBlock, { type: 'image' }>,
  path: string,
  out: PageValidationIssue[]
): void {
  const src = block.src.trim()
  // Allow relative /uploads, https, and data:image — reject javascript: etc.
  if (/^\s*javascript:/i.test(src) || /^\s*data:text\/html/i.test(src)) {
    out.push(
      issue('unsafe_image_src', `${path}.src`, 'Unsafe image src rejected')
    )
  }
}

function semanticValidate(page: PageSpecV1): PageValidationIssue[] {
  const out: PageValidationIssue[] = []

  const jsonBytes = new TextEncoder().encode(JSON.stringify(page)).length
  if (jsonBytes > INTERACTIVE_PAGE_CAPS.maxJsonBytes) {
    out.push(
      issue(
        'json_too_large',
        '',
        `JSON exceeds ${INTERACTIVE_PAGE_CAPS.maxJsonBytes} bytes (${jsonBytes})`
      )
    )
  }

  const demoCount = countDemos(page)
  if (demoCount > INTERACTIVE_PAGE_CAPS.maxDemosPerPage) {
    out.push(
      issue(
        'too_many_demos',
        'sections',
        `At most ${INTERACTIVE_PAGE_CAPS.maxDemosPerPage} demos per page (found ${demoCount})`
      )
    )
  }

  const simCount = countSims(page)
  if (simCount > INTERACTIVE_PAGE_CAPS.maxSimsPerPage) {
    out.push(
      issue(
        'too_many_sims',
        'sections',
        `At most ${INTERACTIVE_PAGE_CAPS.maxSimsPerPage} sims per page (found ${simCount})`
      )
    )
  }

  scanForbiddenColors(page, '', out)

  const sectionIds = new Set<string>()
  for (const [si, section] of page.sections.entries()) {
    const sPath = `sections[${si}]`
    if (sectionIds.has(section.id)) {
      out.push(
        issue(
          'duplicate_section_id',
          `${sPath}.id`,
          `Duplicate section id "${section.id}"`
        )
      )
    }
    sectionIds.add(section.id)

    if (!/^s\d+$/.test(section.id)) {
      out.push(
        issue(
          'section_id_format',
          `${sPath}.id`,
          `Section id should match /^s\\d+$/ (got "${section.id}")`
        )
      )
    }

    for (const [bi, block] of section.blocks.entries()) {
      const bPath = `${sPath}.blocks[${bi}]`

      // Unknown types already hard-rejected by Zod discriminatedUnion.
      if (block.type === 'table') validateTable(block, bPath, out)
      if (block.type === 'image') validateImageSrc(block, bPath, out)
      if (block.type === 'sim') validateSim(block, bPath, out)

      if (block.type === 'demo') {
        const demoResult = validateInteractiveDemo(block.demo)
        if (!demoResult.ok) {
          for (const iss of demoResult.issues) {
            out.push({
              code: `demo_${iss.code}`,
              path: `${bPath}.demo${iss.path ? '.' + iss.path : ''}`,
              message: iss.message,
            })
          }
        }
      }
    }
  }

  return out
}

/**
 * Validate a PageSpecV1 document.
 * Structural (Zod allowlist) then semantic (caps, colors, demos, tables).
 */
export function validateInteractivePage(input: unknown): PageValidationResult {
  const parsed = pageSpecV1Schema.safeParse(input)
  if (!parsed.success) {
    const issues: PageValidationIssue[] = parsed.error.issues.map((e) => ({
      code: e.code,
      path: e.path.join('.'),
      message: e.message,
    }))
    return { ok: false, issues }
  }

  const page = parsed.data as PageSpecV1
  const semantic = semanticValidate(page)
  if (semantic.length > 0) {
    return { ok: false, issues: semantic }
  }
  return { ok: true, page }
}