interface ParsedVersion {
  version: string
  date: string
  features: string[]
  fixes: string[]
  improvements: string[]
  breaking?: string[]
}

export function parseChangelog(markdown: string): ParsedVersion[] {
  const versions: ParsedVersion[] = []
  const versionBlocks = markdown.split(/^#{1,2} \[/m).filter((block) => block.trim())

  for (const block of versionBlocks) {
    const versionMatch = block.match(/^(\d+\.\d+\.\d+)\].*?\((\d{4}-\d{2}-\d{2})\)/)
    if (!versionMatch) continue

    const [, version, date] = versionMatch
    const features: string[] = []
    const fixes: string[] = []
    const improvements: string[] = []
    const breaking: string[] = []

    // Parse features
    const featuresMatch = block.match(/### Features([\s\S]*?)(?=###|$)/i)
    if (featuresMatch) {
      const items = featuresMatch[1].match(/^\* (.+)$/gm) || []
      features.push(
        ...items.map((item) => {
          // Remove the "* " prefix but keep the rest including markdown links
          return item.replace(/^\* /, "").trim()
        }),
      )
    }

    // Parse fixes
    const fixesMatch = block.match(/### Bug Fixes([\s\S]*?)(?=###|$)/i)
    if (fixesMatch) {
      const items = fixesMatch[1].match(/^\* (.+)$/gm) || []
      fixes.push(
        ...items.map((item) => {
          // Remove the "* " prefix but keep the rest including markdown links
          return item.replace(/^\* /, "").trim()
        }),
      )
    }

    // Parse improvements (can be under "Performance", "Refactor", etc.)
    const improvementsMatch = block.match(/### (Performance|Refactor|Improvements)([\s\S]*?)(?=###|$)/i)
    if (improvementsMatch) {
      const items = improvementsMatch[2].match(/^\* (.+)$/gm) || []
      improvements.push(
        ...items.map((item) => {
          // Remove the "* " prefix but keep the rest including markdown links
          return item.replace(/^\* /, "").trim()
        }),
      )
    }

    // Parse breaking changes
    const breakingMatch = block.match(/### BREAKING CHANGES?([\s\S]*?)(?=###|$)/i)
    if (breakingMatch) {
      const items = breakingMatch[1].match(/^\* (.+)$/gm) || []
      breaking.push(
        ...items.map((item) => {
          // Remove the "* " prefix but keep the rest including markdown links
          return item.replace(/^\* /, "").trim()
        }),
      )
    }

    const parsedVersion: ParsedVersion = {
      version,
      date,
      features: features.filter((f) => f.length > 0),
      fixes: fixes.filter((f) => f.length > 0),
      improvements: improvements.filter((f) => f.length > 0),
    }

    if (breaking.length > 0) {
      parsedVersion.breaking = breaking.filter((f) => f.length > 0)
    }

    versions.push(parsedVersion)
  }

  return versions
}

// Capitalize first letter helper
export function capitalizeFirst(text: string): string {
  if (!text) return text
  return text.charAt(0).toUpperCase() + text.slice(1)
}