import type { JSONSchema4 } from 'json-schema'

import { jsonSchemaToZod } from 'json-schema-to-zod'
import * as ts from 'typescript'
import { z } from 'zod'

import { sanitizeJsonSchema } from './sanitizeJsonSchema.js'
import { simplifyRelationshipFields } from './simplifyRelationshipFields.js'
import { transformPointFieldsForMCP } from './transformPointFields.js'

export const convertCollectionSchemaToZod = (schema: JSONSchema4) => {
  try {
    // Clone to avoid mutating the original schema (used elsewhere for tool listing)
    const schemaClone = JSON.parse(JSON.stringify(schema)) as JSONSchema4

    const sanitized = sanitizeJsonSchema(schemaClone)
    const pointTransformed = transformPointFieldsForMCP(sanitized)
    const zodSchemaAsString = jsonSchemaToZod(simplifyRelationshipFields(pointTransformed))

    // Transpile TypeScript to JavaScript
    const transpileResult = ts.transpileModule(zodSchemaAsString, {
      compilerOptions: {
        module: ts.ModuleKind.CommonJS,
        removeComments: true,
        strict: false,
        target: ts.ScriptTarget.ES2018,
      },
    })

    /**
     * This Function evaluation is safe because:
     * 1. The input schema comes from Payload's collection configuration, which is controlled by the application developer
     * 2. The jsonSchemaToZod library converts JSON Schema to Zod schema definitions, producing only type validation code
     * 3. The transpiled output contains only Zod schema definitions (z.string(), z.number(), etc.) - no executable logic
     * 4. The resulting Zod schema is used only for parameter validation in MCP tools, not for data processing
     * 5. No user input or external data is involved in the schema generation process
     */
    // eslint-disable-next-line @typescript-eslint/no-implied-eval
    return new Function('z', `return ${transpileResult.outputText}`)(z)
  } catch (error) {
    // If schema conversion fails (e.g., due to Zod v4 toJSONSchema null-check bug
    // with record schemas that have undefined valueType, or bundler transforms
    // stripping Zod internals), return a permissive schema so tools/list doesn't
    // crash entirely. The tool will still be listed but without strict validation.
    // See: https://github.com/colinhacks/zod/issues/5821
    console.warn(
      `[plugin-mcp] Schema conversion failed, using permissive fallback:`,
      error instanceof Error ? error.message : error,
    )
    return z.record(z.any())
  }
}