import { getActiveProfileDir } from '../../services/hermes/hermes-profile'

const SQLITE_AVAILABLE = (() => {
  const [major, minor] = process.versions.node.split('.').map(Number)
  return major > 22 || (major === 22 && minor >= 5)
})()

export interface HermesSessionRow {
  id: string
  source: string
  user_id: string | null
  model: string
  title: string | null
  started_at: number
  ended_at: number | null
  end_reason: string | null
  message_count: number
  tool_call_count: number
  input_tokens: number
  output_tokens: number
  cache_read_tokens: number
  cache_write_tokens: number
  reasoning_tokens: number
  billing_provider: string | null
  estimated_cost_usd: number
  actual_cost_usd: number | null
  cost_status: string
  preview: string
  last_active: number
}

export interface HermesSessionSearchRow extends HermesSessionRow {
  matched_message_id: number | null
  snippet: string
  rank: number
}

function sessionDbPath(): string {
  return `${getActiveProfileDir()}/state.db`
}

function normalizeNumber(value: unknown, fallback = 0): number {
  if (value == null || value === '') return fallback
  const num = Number(value)
  return Number.isFinite(num) ? num : fallback
}

function normalizeNullableNumber(value: unknown): number | null {
  if (value == null || value === '') return null
  const num = Number(value)
  return Number.isFinite(num) ? num : null
}

function normalizeNullableString(value: unknown): string | null {
  if (value == null || value === '') return null
  return String(value)
}

function mapRow(row: Record<string, unknown>): HermesSessionRow {
  const startedAt = normalizeNumber(row.started_at)
  const rawTitle = normalizeNullableString(row.title)
  const preview = String(row.preview || '')
  // Fallback: when no explicit title, use first user message as title (same as CLI path)
  const title = rawTitle || (preview ? (preview.length > 40 ? preview.slice(0, 40) + '...' : preview) : null)
  return {
    id: String(row.id || ''),
    source: String(row.source || ''),
    user_id: normalizeNullableString(row.user_id),
    model: String(row.model || ''),
    title,
    started_at: startedAt,
    ended_at: normalizeNullableNumber(row.ended_at),
    end_reason: normalizeNullableString(row.end_reason),
    message_count: normalizeNumber(row.message_count),
    tool_call_count: normalizeNumber(row.tool_call_count),
    input_tokens: normalizeNumber(row.input_tokens),
    output_tokens: normalizeNumber(row.output_tokens),
    cache_read_tokens: normalizeNumber(row.cache_read_tokens),
    cache_write_tokens: normalizeNumber(row.cache_write_tokens),
    reasoning_tokens: normalizeNumber(row.reasoning_tokens),
    billing_provider: normalizeNullableString(row.billing_provider),
    estimated_cost_usd: normalizeNumber(row.estimated_cost_usd),
    actual_cost_usd: normalizeNullableNumber(row.actual_cost_usd),
    cost_status: String(row.cost_status || ''),
    preview: String(row.preview || ''),
    last_active: normalizeNumber(row.last_active, startedAt),
  }
}

const SESSION_SELECT = `
  s.id,
  s.source,
  COALESCE(s.user_id, '') AS user_id,
  COALESCE(s.model, '') AS model,
  COALESCE(s.title, '') AS title,
  COALESCE(s.started_at, 0) AS started_at,
  s.ended_at AS ended_at,
  COALESCE(s.end_reason, '') AS end_reason,
  COALESCE(s.message_count, 0) AS message_count,
  COALESCE(s.tool_call_count, 0) AS tool_call_count,
  COALESCE(s.input_tokens, 0) AS input_tokens,
  COALESCE(s.output_tokens, 0) AS output_tokens,
  COALESCE(s.cache_read_tokens, 0) AS cache_read_tokens,
  COALESCE(s.cache_write_tokens, 0) AS cache_write_tokens,
  COALESCE(s.reasoning_tokens, 0) AS reasoning_tokens,
  COALESCE(s.billing_provider, '') AS billing_provider,
  COALESCE(s.estimated_cost_usd, 0) AS estimated_cost_usd,
  s.actual_cost_usd AS actual_cost_usd,
  COALESCE(s.cost_status, '') AS cost_status,
  COALESCE(
    (
      SELECT SUBSTR(REPLACE(REPLACE(m.content, CHAR(10), ' '), CHAR(13), ' '), 1, 63)
      FROM messages m
      WHERE m.session_id = s.id AND m.role = 'user' AND m.content IS NOT NULL
      ORDER BY m.timestamp, m.id
      LIMIT 1
    ),
    ''
  ) AS preview,
  COALESCE((SELECT MAX(m2.timestamp) FROM messages m2 WHERE m2.session_id = s.id), s.started_at) AS last_active
`

const SESSION_FROM = `
  FROM sessions s
  WHERE s.parent_session_id IS NULL
    AND s.source != 'tool'
`

function buildBaseSessionSql(source?: string): { sql: string, params: any[] } {
  const sql = source
    ? `SELECT ${SESSION_SELECT}${SESSION_FROM}\n    AND s.source = ?`
    : `SELECT ${SESSION_SELECT}${SESSION_FROM}`
  return { sql, params: source ? [source] : [] }
}

function buildListSessionSql(source?: string, limit = 2000): { sql: string, params: any[] } {
  const base = buildBaseSessionSql(source)
  return {
    sql: `${base.sql}\n  ORDER BY s.started_at DESC\n  LIMIT ?`,
    params: [...base.params, limit],
  }
}

function containsCjk(text: string): boolean {
  for (const ch of text) {
    const cp = ch.codePointAt(0) ?? 0
    if (
      (cp >= 0x4E00 && cp <= 0x9FFF) ||
      (cp >= 0x3400 && cp <= 0x4DBF) ||
      (cp >= 0x20000 && cp <= 0x2A6DF) ||
      (cp >= 0x3000 && cp <= 0x303F) ||
      (cp >= 0x3040 && cp <= 0x309F) ||
      (cp >= 0x30A0 && cp <= 0x30FF) ||
      (cp >= 0xAC00 && cp <= 0xD7AF)
    ) {
      return true
    }
  }
  return false
}

function isNumericQuery(text: string): boolean {
  return /^\d+(?:\s+\d+)*$/.test(text.trim())
}

function runLikeContentSearch(
  db: { prepare: (sql: string) => { all: (...params: any[]) => Record<string, unknown>[] } },
  source: string | undefined,
  query: string,
): Record<string, unknown>[] {
  const likeBase = buildBaseSessionSql(source)
  const likeSql = `
    WITH base AS (
      ${likeBase.sql}
    )
    SELECT
      base.*,
      m.id AS matched_message_id,
      substr(
        m.content,
        max(1, instr(m.content, ?) - 40),
        120
      ) AS snippet,
      0 AS rank
    FROM base
    JOIN messages m ON m.session_id = base.id
    WHERE m.content LIKE ?
    ORDER BY base.last_active DESC, m.timestamp DESC
  `
  const likeStatement = db.prepare(likeSql)
  return likeStatement.all(...likeBase.params, query, `%${query}%`) as Record<string, unknown>[]
}

function sanitizeFtsQuery(query: string): string {
  const quotedParts: string[] = []

  const preserved = query.replace(/"[^"]*"/g, (match) => {
    quotedParts.push(match)
    return `\u0000Q${quotedParts.length - 1}\u0000`
  })

  let sanitized = preserved.replace(/[+{}()"^]/g, ' ')
  sanitized = sanitized.replace(/\*+/g, '*')
  sanitized = sanitized.replace(/(^|\s)\*/g, '$1')
  sanitized = sanitized.trim().replace(/^(AND|OR|NOT)\b\s*/i, '')
  sanitized = sanitized.trim().replace(/\s+(AND|OR|NOT)\s*$/i, '')
  sanitized = sanitized.replace(/\b(\w+(?:[.-]\w+)+)\b/g, '"$1"')

  for (let i = 0; i < quotedParts.length; i += 1) {
    sanitized = sanitized.replace(`\u0000Q${i}\u0000`, quotedParts[i])
  }

  return sanitized.trim()
}

function toPrefixQuery(query: string): string {
  const tokens = query.match(/"[^"]*"|\S+/g)
  if (!tokens) return ''
  return tokens
    .map((token) => {
      if (token === 'AND' || token === 'OR' || token === 'NOT') return token
      if (token.startsWith('"') && token.endsWith('"')) return token
      if (token.endsWith('*')) return token
      return `${token}*`
    })
    .join(' ')
}

function mapSearchRow(row: Record<string, unknown>): HermesSessionSearchRow {
  return {
    ...mapRow(row),
    matched_message_id: normalizeNullableNumber(row.matched_message_id),
    snippet: String(row.snippet || row.preview || ''),
    rank: Number.isFinite(Number(row.rank)) ? Number(row.rank) : 0,
  }
}

export async function listSessionSummaries(source?: string, limit = 2000): Promise<HermesSessionRow[]> {
  if (!SQLITE_AVAILABLE) {
    throw new Error(`node:sqlite requires Node >= 22.5, current: ${process.versions.node}`)
  }

  const { DatabaseSync } = await import('node:sqlite')
  const db = new DatabaseSync(sessionDbPath(), { open: true, readOnly: true })

  try {
    const { sql, params } = buildListSessionSql(source, limit)
    const statement = db.prepare(sql)
    const rows = statement.all(...params) as Record<string, unknown>[]

    return rows.map(mapRow)
  } finally {
    db.close()
  }
}

export async function searchSessionSummaries(
  query: string,
  source?: string,
  limit = 20,
): Promise<HermesSessionSearchRow[]> {
  if (!SQLITE_AVAILABLE) {
    throw new Error(`node:sqlite requires Node >= 22.5, current: ${process.versions.node}`)
  }

  const trimmed = query.trim()
  if (!trimmed) {
    const recent = await listSessionSummaries(source, limit)
    return recent.map(row => ({
      ...row,
      matched_message_id: null,
      snippet: row.preview,
      rank: 0,
    }))
  }

  const { DatabaseSync } = await import('node:sqlite')
  const db = new DatabaseSync(sessionDbPath(), { open: true, readOnly: true })
  const normalized = sanitizeFtsQuery(trimmed)
  const prefixQuery = toPrefixQuery(normalized)
  let titleRows: Record<string, unknown>[] = []

  try {
    const titleBase = buildBaseSessionSql(source)
    const contentBase = buildBaseSessionSql(source)

    const titleSql = `
      WITH base AS (
        ${titleBase.sql}
      )
      SELECT
        base.*,
        NULL AS matched_message_id,
        CASE
          WHEN base.title IS NOT NULL AND base.title != '' THEN base.title
          ELSE base.preview
        END AS snippet,
        0 AS rank
      FROM base
      WHERE LOWER(COALESCE(base.title, '')) LIKE ?
      ORDER BY base.last_active DESC
      LIMIT ?
    `

    const titleStatement = db.prepare(titleSql)
    titleRows = titleStatement.all(...titleBase.params, `%${trimmed.toLowerCase()}%`, limit) as Record<string, unknown>[]

    const contentSql = `
      WITH base AS (
        ${contentBase.sql}
      )
      SELECT
        base.*,
        m.id AS matched_message_id,
        snippet(messages_fts, 0, '>>>', '<<<', '...', 40) AS snippet,
        bm25(messages_fts) AS rank
      FROM messages_fts
      JOIN messages m ON m.id = messages_fts.rowid
      JOIN base ON base.id = m.session_id
      WHERE messages_fts MATCH ?
      ORDER BY rank, base.last_active DESC
      LIMIT ?
    `

    const contentRows = prefixQuery
      ? (db.prepare(contentSql).all(...contentBase.params, prefixQuery, limit * 4) as Record<string, unknown>[])
      : []

    const merged = new Map<string, HermesSessionSearchRow>()
    for (const row of titleRows) {
      const mapped = mapSearchRow(row)
      merged.set(mapped.id, mapped)
    }
    for (const row of contentRows) {
      const mapped = mapSearchRow(row)
      if (!merged.has(mapped.id)) {
        merged.set(mapped.id, mapped)
      }
    }

    const items = [...merged.values()]
    items.sort((a, b) => {
      if (a.rank !== b.rank) return a.rank - b.rank
      return b.last_active - a.last_active
    })
    return items.slice(0, limit)
  } catch (err) {
    const message = err instanceof Error ? err.message : String(err)
    if (containsCjk(normalized)) {
      const likeRows = runLikeContentSearch(db, source, trimmed)
      const merged = new Map<string, HermesSessionSearchRow>()
      for (const row of likeRows) {
        const mapped = mapSearchRow(row)
        if (!merged.has(mapped.id)) {
          merged.set(mapped.id, mapped)
        }
      }
      return [...merged.values()].slice(0, limit)
    }

    if (message.includes('no such table: messages_fts') && isNumericQuery(trimmed)) {
      const likeRows = runLikeContentSearch(db, source, trimmed)
      const merged = new Map<string, HermesSessionSearchRow>()
      for (const row of titleRows) {
        const mapped = mapSearchRow(row)
        merged.set(mapped.id, mapped)
      }
      for (const row of likeRows) {
        const mapped = mapSearchRow(row)
        if (!merged.has(mapped.id)) {
          merged.set(mapped.id, mapped)
        }
      }
      return [...merged.values()].slice(0, limit)
    }

    throw new Error(`Failed to search sessions: ${message}`)
  } finally {
    db.close()
  }
}