export function getStepGenerationPrompt(params: {
  city: string
  dayNumber: number
  totalDays: number
  dayTheme: string
  pace: string
  companions: string
  userComment?: string
  previousPoints: string[]
  lang: string
}): string {
  const langInstruction = params.lang === 'ru'
    ? 'Write title and teaserText in Russian.'
    : 'Write title and teaserText in English.'

  return `Given quest context:
- City: ${params.city}
- Day: ${params.dayNumber} of ${params.totalDays}
- Day theme: ${params.dayTheme}
- Pace: ${params.pace}
- Companions: ${params.companions}
${params.userComment ? `- User wishes: ${params.userComment}` : ''}
- Points already visited today: ${params.previousPoints.length > 0 ? params.previousPoints.join(', ') : 'none (this is the first point)'}

Generate the NEXT point for today's route.

${langInstruction}

Return ONLY a valid JSON object:
{
  "title": "Location name",
  "teaserText": "1-2 sentences teasing what awaits, creating curiosity",
  "locationLat": <number>,
  "locationLon": <number>,
  "isLastPointOfDay": <boolean>
}

Requirements:
- Must be a REAL location in ${params.city} with accurate coordinates
- Must be geographically close to the previous point (walkable)
- Must not repeat any visited location
- Teaser should create curiosity without spoiling
- Consider the narrative arc of the day
- For ${params.pace} pace: ${{slow: '4-5 points per day', normal: '5-7 points per day', active: '7-9 points per day'}[params.pace] || '5-7 points per day'}
- Set isLastPointOfDay=true when it makes sense to end the day

Return ONLY valid JSON, no markdown, no extra text.`
}