import type { ContentType } from "./content-types"

// Escape characters that would break markdown table cells
const mdCell = (s: string) => s.replace(/\|/g, "\\|").replace(/\n/g, " ")

export interface ExportBlock {
  id: string
  text: string
  contentType: ContentType
  category?: string
  annotation?: string
  confidence?: number | null
  sources?: { url: string; title: string; siteName: string }[]
  isPinned?: boolean
  timestamp?: number
}

// ── Type ordering — research-logical flow ─────────────────────────────────────

const TYPE_ORDER: ContentType[] = [
  "thesis",
  "claim",
  "question",
  "idea",
  "task",
  "entity",
  "definition",
  "reference",
  "quote",
  "opinion",
  "reflection",
  "narrative",
  "comparison",
  "general",
]

const TYPE_META: Record<ContentType, { heading: string; emoji: string; description: string }> = {
  thesis:     { heading: "Thesis",      emoji: "🔬", description: "Synthesised conclusions" },
  claim:      { heading: "Claims",      emoji: "⚡", description: "Assertions with confidence scores" },
  question:   { heading: "Questions",   emoji: "❓", description: "Open threads and unknowns" },
  idea:       { heading: "Ideas",       emoji: "💡", description: "Raw concepts and hunches" },
  task:       { heading: "Tasks",       emoji: "✅", description: "Action items" },
  entity:     { heading: "Entities",    emoji: "🏷️",  description: "People, places, and named concepts" },
  definition: { heading: "Definitions", emoji: "📖", description: "Terminology and explanations" },
  reference:  { heading: "References",  emoji: "🔗", description: "Sources and links" },
  quote:      { heading: "Quotes",      emoji: "💬", description: "Direct quotations" },
  opinion:    { heading: "Opinions",    emoji: "🗣️",  description: "Subjective takes" },
  reflection: { heading: "Reflections", emoji: "🪞", description: "Personal observations" },
  narrative:  { heading: "Narratives",  emoji: "📜", description: "Extended accounts" },
  comparison: { heading: "Comparisons", emoji: "⚖️",  description: "Contrasts and parallels" },
  general:    { heading: "Notes",       emoji: "📝", description: "Miscellaneous notes" },
}

// ── Helpers ───────────────────────────────────────────────────────────────────

function formatDate(ts?: number): string {
  const d = ts ? new Date(ts) : new Date()
  return d.toLocaleDateString("en-GB", { day: "numeric", month: "long", year: "numeric" })
}

function formatTime(ts?: number): string {
  if (!ts) return ""
  return new Date(ts).toLocaleTimeString([], { hour: "2-digit", minute: "2-digit" })
}

/** Five-block filled/empty bar + percentage */
function confidenceBar(c: number): string {
  const clamped = Math.min(100, Math.max(0, c))
  const pct     = Math.round(clamped)
  const filled  = Math.round((clamped / 100) * 5)
  const bar     = "█".repeat(filled) + "░".repeat(5 - filled)
  return `${bar} ${pct}%`
}

/** Anchor-safe slug for TOC links */
function slug(text: string): string {
  return text
    .toLowerCase()
    .replace(/[^a-z0-9\s-]/g, "")
    .trim()
    .replace(/\s+/g, "-")
    .slice(0, 50)
}

// ── Main export ───────────────────────────────────────────────────────────────

/**
 * Export a project as a richly-formatted Markdown document.
 * Uses YAML front matter, a table of contents, grouped sections,
 * tables for claims, task lists, blockquotes, inline code, and source links
 * so the output renders well in GitHub, Obsidian, Notion, and any LLM context.
 */
export function exportToMarkdown(projectName: string, blocks: ExportBlock[]): string {
  if (blocks.length === 0) {
    return [
      `# ${projectName}`,
      ``,
      `> _No nodes yet._`,
      ``,
      `---`,
      `*Generated by [nodepad](https://nodepad.space)*`,
    ].join("\n")
  }

  // Group by type
  const byType = new Map<ContentType, ExportBlock[]>()
  for (const block of blocks) {
    const t = block.contentType || "general"
    if (!byType.has(t)) byType.set(t, [])
    byType.get(t)!.push(block)
  }

  const presentTypes = TYPE_ORDER.filter(t => (byType.get(t)?.length ?? 0) > 0)
  const date         = formatDate(blocks[0]?.timestamp)
  const pinned       = blocks.filter(b => b.isPinned)

  const lines: string[] = []

  // ── YAML front matter ─────────────────────────────────────────────────────
  lines.push(`---`)
  lines.push(`title: "${projectName}"`)
  lines.push(`date: "${date}"`)
  lines.push(`nodes: ${blocks.length}`)
  lines.push(`types: [${presentTypes.map(t => `"${t}"`).join(", ")}]`)
  lines.push(`source: nodepad — https://nodepad.space`)
  lines.push(`---`)
  lines.push(``)

  // ── Title block ───────────────────────────────────────────────────────────
  lines.push(`# ${projectName}`)
  lines.push(``)
  lines.push(`> **Generated by [nodepad](https://nodepad.space)** · ${date} · ${blocks.length} node${blocks.length !== 1 ? "s" : ""}`)
  lines.push(``)

  // ── Stats table ───────────────────────────────────────────────────────────
  lines.push(`## Overview`)
  lines.push(``)
  lines.push(`| Type | Count |`)
  lines.push(`|------|-------|`)
  for (const type of presentTypes) {
    const { emoji, heading } = TYPE_META[type]
    lines.push(`| ${emoji} ${heading} | ${byType.get(type)!.length} |`)
  }
  lines.push(``)

  // ── Pinned notes callout (if any) ─────────────────────────────────────────
  if (pinned.length > 0) {
    lines.push(`> **📌 Pinned nodes**`)
    for (const b of pinned) {
      lines.push(`> - ${b.text}`)
    }
    lines.push(``)
  }

  // ── Table of contents ─────────────────────────────────────────────────────
  lines.push(`## Contents`)
  lines.push(``)
  for (const type of presentTypes) {
    const { emoji, heading } = TYPE_META[type]
    const count = byType.get(type)!.length
    lines.push(`- [${emoji} ${heading}](#${slug(heading)}) *(${count})*`)
  }
  lines.push(``)

  // ── Sections ──────────────────────────────────────────────────────────────
  for (const type of presentTypes) {
    const group = byType.get(type)!
    const { emoji, heading, description } = TYPE_META[type]

    lines.push(`---`)
    lines.push(``)
    lines.push(`## ${emoji} ${heading}`)
    lines.push(``)
    lines.push(`*${description}*`)
    lines.push(``)

    // Claims → table for scannability
    if (type === "claim") {
      lines.push(`| Claim | Category | Confidence | AI Annotation |`)
      lines.push(`|-------|----------|------------|---------------|`)
      for (const block of group) {
        const cat   = block.category ? `\`${mdCell(block.category)}\`` : "—"
        const conf  = block.confidence != null
          ? `\`${confidenceBar(block.confidence)}\``
          : "—"
        const annot = block.annotation
          ? block.annotation.replace(/\n/g, " ").replace(/\|/g, "\\|").slice(0, 120) + (block.annotation.length > 120 ? "…" : "")
          : "—"
        lines.push(`| **${block.text.replace(/\|/g, "\\|")}** | ${cat} | ${conf} | ${annot} |`)
      }
      lines.push(``)
      continue
    }

    // Tasks → GFM task list
    if (type === "task") {
      for (const block of group) {
        lines.push(`- [ ] **${block.text}**`)
        if (block.category) lines.push(`  - Category: \`${block.category}\``)
        if (block.annotation) {
          lines.push(`  - > ${block.annotation.replace(/\n/g, " ")}`)
        }
      }
      lines.push(``)
      continue
    }

    // Quotes → blockquote with attribution styling
    if (type === "quote") {
      for (const block of group) {
        lines.push(`> ${block.text}`)
        if (block.category)  lines.push(`>`)
        if (block.category)  lines.push(`> — \`${block.category}\``)
        if (block.annotation) {
          lines.push(`>`)
          lines.push(`> *${block.annotation.replace(/\n/g, " ")}*`)
        }
        lines.push(``)
      }
      continue
    }

    // All other types → heading + metadata + annotation
    for (const block of group) {
      lines.push(`### ${block.text}`)
      lines.push(``)

      // Metadata row
      const meta: string[] = []
      if (block.category)  meta.push(`**Category:** \`${block.category}\``)
      if (block.timestamp) meta.push(`**Added:** ${formatDate(block.timestamp)} ${formatTime(block.timestamp)}`)
      if (block.isPinned)  meta.push(`📌 *Pinned*`)
      if (meta.length > 0) {
        lines.push(meta.join(" · "))
        lines.push(``)
      }

      // AI annotation as blockquote
      if (block.annotation) {
        lines.push(`> **AI Annotation**`)
        for (const l of block.annotation.split("\n")) {
          lines.push(`> ${l}`)
        }
        lines.push(``)
      }

      // Sources as a nested list
      if (block.sources && block.sources.length > 0) {
        lines.push(`**Sources**`)
        lines.push(``)
        for (const s of block.sources) {
          const label = s.title || s.siteName || s.url
          lines.push(`- [${label}](${s.url})${s.siteName ? ` *(${s.siteName})*` : ""}`)
        }
        lines.push(``)
      }
    }
  }

  // ── Footer ────────────────────────────────────────────────────────────────
  lines.push(`---`)
  lines.push(``)
  lines.push(`*Generated by [nodepad](https://nodepad.space) · ${date}*`)
  lines.push(``)

  return lines.join("\n")
}

// ── Download / clipboard helpers ─────────────────────────────────────────────

/** Trigger a browser download of a .md file. */
export function downloadMarkdown(filename: string, content: string): void {
  const blob = new Blob([content], { type: "text/markdown;charset=utf-8" })
  const url  = URL.createObjectURL(blob)
  const a    = document.createElement("a")
  a.href     = url
  a.download = filename
  a.click()
  URL.revokeObjectURL(url)
}

/** Copy content to clipboard. Returns true on success. */
export async function copyToClipboard(content: string): Promise<boolean> {
  try {
    await navigator.clipboard.writeText(content)
    return true
  } catch {
    return false
  }
}