import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
import { z } from 'zod'
import type { SceneOperations } from '../operations'
import { SCENE_DESIGN_GUIDANCE } from './scene-guidance'

const PREAMBLE = [
  'You are a Pascal 3D scene designer.',
  'You have access to semantic scene tools and the lower-level `apply_patch` tool. Prefer semantic construction/room/opening/furnishing tools for architectural work, and use `apply_patch` for bulk graph edits that need exact control.',
  'If the user asks for a new project, call `create_project` before building. Use `create_house_from_brief` for a fast starter, then refine with semantic tools. Semantic tools update the browser-visible draft; call `save_scene` with `saveMode: "checkpoint"` only for meaningful milestones, then call `verify_scene` and `get_project_status`, and return the final `editorUrl`.',
  'Build incrementally with visible progress. Starting from an empty scene, first create/load a Site and Building, then create occupied Levels and `create_story_shell` once per story before detailed rooms, openings, furniture, a dedicated roof level via `create_roof`, and landscaping.',
  'Respect these invariants:',
  '  - Levels live under a Building.',
  '  - Walls, fences, zones, slabs, ceilings, roofs, stairs live under a Level.',
  '  - Multi-story exterior walls are per-level story walls; never make lower-level walls taller to stand in for upper-level walls.',
  '  - Doors and windows live under a Wall (parentId = wallId).',
  '  - Floor items live under a Level; wall/ceiling-attached items live under their target Wall or Ceiling. Do not place items directly under the Site node.',
  'Use realistic dimensions in meters. Keep wall thickness small (0.1–0.3 m) and ceiling height 2.4–3.0 m unless the brief dictates otherwise.',
  SCENE_DESIGN_GUIDANCE,
  'Respond ONLY with tool calls. Do not produce verbose narrative or prose; keep any explanations in short tool-call arguments.',
].join('\n')

/**
 * Build the user-facing prompt text for `from_brief`. Pure function for testability.
 */
export function buildFromBriefPrompt(args: {
  brief: string
  constraints?: string | undefined
}): string {
  const parts: string[] = [PREAMBLE, '', '## Brief', args.brief.trim()]
  if (args.constraints && args.constraints.trim().length > 0) {
    parts.push('', '## Constraints', args.constraints.trim())
  }
  parts.push(
    '',
    '## Task',
    'Produce tool calls that realise the brief within the stated constraints. For a new project, call create_project first. Use create_house_from_brief for a fast starter or prefer create_story_shell/create_room/add_door/add_window/create_stair_between_levels/create_roof/furnish_room for architectural layout, use apply_patch for exact bulk graph work, call save_scene with saveMode: "checkpoint" only when the design reaches a meaningful milestone, then call validate_scene, verify_scene, and get_project_status.',
  )
  return parts.join('\n')
}

export function registerFromBrief(server: McpServer, _bridge: SceneOperations): void {
  server.registerPrompt(
    'from_brief',
    {
      title: 'Generate a Pascal scene from a brief',
      description:
        'Produces a plan of apply_patch calls to create a scene from a natural-language brief.',
      argsSchema: {
        brief: z.string(),
        constraints: z.string().optional(),
      },
    },
    async ({ brief, constraints }) => ({
      messages: [
        {
          role: 'user',
          content: {
            type: 'text',
            text: buildFromBriefPrompt({ brief, constraints }),
          },
        },
      ],
    }),
  )
}