import Database from 'better-sqlite3'
import { mkdirSync } from 'fs'
import { dirname } from 'path'
import type { SessionMeta } from '../../types/session.js'

export interface ListFilters {
  days?: number
  project?: string
  tool?: string
  skill?: string
  q?: string
  limit?: number
  offset?: number
}

export interface PatternRecord {
  id?: number
  detected_at: string
  week_iso: string
  pattern_key: string
  title: string
  description: string
  severity: 'info' | 'warning' | 'action'
  metric_value: number | null
  sample_session_ids: string[]
  affected_count: number
  consecutive_weeks: number
}

export interface WorklogCommentRecord {
  id: number
  discussion_id: number
  created_at: string
  staff_id: number | null
  title: string | null
  task_ref: string | null
  duration_sec: number | null
  work_items: string[]
  files_modified: string[]
  problems: { problema: string; solucao: string }[]
  patterns_text: string[]
  actions: { tipo: string; descricao: string; prioridade: string | null }[]
  raw_html: string
  imported_at: string
}

export interface WorklogFilters {
  discussion_id?: number
  task_ref?: string
  sinceIso?: string
  limit?: number
  offset?: number
}

export interface SessionsDb {
  upsertSession(meta: SessionMeta): void
  upsertMany(metas: SessionMeta[]): void
  listSessions(filters: ListFilters): SessionMeta[]
  countSessions(filters: ListFilters): number
  getSession(id: string): SessionMeta | null
  deleteByJsonlPath(path: string): void
  upsertPattern(p: PatternRecord): void
  getPatternsByWeek(week: string): PatternRecord[]
  getConsecutiveWeeks(pattern_key: string, uptoWeek: string): number
  upsertWorklogComment(c: WorklogCommentRecord): { inserted: boolean }
  hasWorklogComment(id: number): boolean
  listWorklogComments(filters: WorklogFilters): WorklogCommentRecord[]
  countWorklogComments(filters?: WorklogFilters): number
  rawDb(): Database.Database
  close(): void
}

const SCHEMA = `
CREATE TABLE IF NOT EXISTS sessions (
  session_id      TEXT PRIMARY KEY,
  project_path    TEXT NOT NULL,
  project_slug    TEXT NOT NULL,
  jsonl_path      TEXT NOT NULL UNIQUE,
  started_at      TEXT NOT NULL,
  ended_at        TEXT,
  duration_sec    INTEGER,
  event_count     INTEGER NOT NULL,
  user_messages   INTEGER NOT NULL,
  assistant_msgs  INTEGER NOT NULL,
  tool_calls      INTEGER NOT NULL,
  first_prompt    TEXT,
  tools_used      TEXT NOT NULL,
  skills_invoked  TEXT NOT NULL,
  outcome         TEXT NOT NULL,
  permission_mode TEXT,
  file_size       INTEGER NOT NULL,
  indexed_at      TEXT NOT NULL
);
CREATE INDEX IF NOT EXISTS idx_started ON sessions(started_at DESC);
CREATE INDEX IF NOT EXISTS idx_project ON sessions(project_slug, started_at DESC);

CREATE TABLE IF NOT EXISTS patterns (
  id              INTEGER PRIMARY KEY AUTOINCREMENT,
  detected_at     TEXT NOT NULL,
  week_iso        TEXT NOT NULL,
  pattern_key     TEXT NOT NULL,
  title           TEXT NOT NULL,
  description     TEXT NOT NULL,
  severity        TEXT NOT NULL,
  metric_value    REAL,
  sample_session_ids TEXT NOT NULL,
  affected_count  INTEGER NOT NULL,
  consecutive_weeks INTEGER NOT NULL DEFAULT 1,
  UNIQUE(week_iso, pattern_key)
);
CREATE INDEX IF NOT EXISTS idx_patterns_week ON patterns(week_iso);
CREATE INDEX IF NOT EXISTS idx_patterns_key ON patterns(pattern_key);

CREATE TABLE IF NOT EXISTS worklog_comments (
  id              INTEGER PRIMARY KEY,
  discussion_id   INTEGER NOT NULL,
  created_at      TEXT NOT NULL,
  staff_id        INTEGER,
  title           TEXT,
  task_ref        TEXT,
  duration_sec    INTEGER,
  work_items      TEXT NOT NULL,
  files_modified  TEXT NOT NULL,
  problems_json   TEXT NOT NULL,
  patterns_text   TEXT NOT NULL,
  actions_json    TEXT NOT NULL,
  raw_html        TEXT NOT NULL,
  imported_at     TEXT NOT NULL
);
CREATE INDEX IF NOT EXISTS idx_wc_discussion ON worklog_comments(discussion_id, created_at DESC);
CREATE INDEX IF NOT EXISTS idx_wc_task ON worklog_comments(task_ref);
`

function rowToMeta(row: Record<string, unknown>): SessionMeta {
  return {
    session_id: row.session_id as string,
    project_path: row.project_path as string,
    project_slug: row.project_slug as string,
    jsonl_path: row.jsonl_path as string,
    started_at: row.started_at as string,
    ended_at: (row.ended_at as string | null) ?? null,
    duration_sec: (row.duration_sec as number | null) ?? null,
    event_count: row.event_count as number,
    user_messages: row.user_messages as number,
    assistant_msgs: row.assistant_msgs as number,
    tool_calls: row.tool_calls as number,
    first_prompt: (row.first_prompt as string | null) ?? null,
    tools_used: JSON.parse(row.tools_used as string),
    skills_invoked: JSON.parse(row.skills_invoked as string),
    outcome: row.outcome as SessionMeta['outcome'],
    permission_mode: (row.permission_mode as string | null) ?? null,
    file_size: row.file_size as number,
    indexed_at: row.indexed_at as string,
  }
}

function buildWhere(f: ListFilters): { sql: string; params: Record<string, unknown> } {
  const parts: string[] = []
  const params: Record<string, unknown> = {}
  if (f.days) {
    const cutoff = new Date(Date.now() - f.days * 86400_000).toISOString()
    parts.push('started_at >= @cutoff')
    params.cutoff = cutoff
  }
  if (f.project) {
    parts.push('project_slug = @project')
    params.project = f.project
  }
  if (f.tool) {
    parts.push("tools_used LIKE @toolLike")
    params.toolLike = `%"${f.tool}"%`
  }
  if (f.skill) {
    parts.push('skills_invoked LIKE @skillLike')
    params.skillLike = `%"${f.skill}"%`
  }
  if (f.q) {
    parts.push('first_prompt LIKE @q')
    params.q = `%${f.q}%`
  }
  return {
    sql: parts.length ? 'WHERE ' + parts.join(' AND ') : '',
    params,
  }
}

export function openSessionsDb(dbPath: string): SessionsDb {
  mkdirSync(dirname(dbPath), { recursive: true })
  const db = new Database(dbPath)
  db.pragma('journal_mode = WAL')
  db.pragma('synchronous = NORMAL')
  db.exec(SCHEMA)

  const upsertStmt = db.prepare(`
    INSERT INTO sessions (session_id, project_path, project_slug, jsonl_path, started_at, ended_at,
      duration_sec, event_count, user_messages, assistant_msgs, tool_calls, first_prompt,
      tools_used, skills_invoked, outcome, permission_mode, file_size, indexed_at)
    VALUES (@session_id, @project_path, @project_slug, @jsonl_path, @started_at, @ended_at,
      @duration_sec, @event_count, @user_messages, @assistant_msgs, @tool_calls, @first_prompt,
      @tools_used, @skills_invoked, @outcome, @permission_mode, @file_size, @indexed_at)
    ON CONFLICT(session_id) DO UPDATE SET
      project_path = excluded.project_path,
      project_slug = excluded.project_slug,
      jsonl_path = excluded.jsonl_path,
      started_at = excluded.started_at,
      ended_at = excluded.ended_at,
      duration_sec = excluded.duration_sec,
      event_count = excluded.event_count,
      user_messages = excluded.user_messages,
      assistant_msgs = excluded.assistant_msgs,
      tool_calls = excluded.tool_calls,
      first_prompt = excluded.first_prompt,
      tools_used = excluded.tools_used,
      skills_invoked = excluded.skills_invoked,
      outcome = excluded.outcome,
      permission_mode = excluded.permission_mode,
      file_size = excluded.file_size,
      indexed_at = excluded.indexed_at
  `)

  const upsertManyTxn = db.transaction((metas: SessionMeta[]) => {
    for (const meta of metas) {
      upsertStmt.run({
        ...meta,
        tools_used: JSON.stringify(meta.tools_used),
        skills_invoked: JSON.stringify(meta.skills_invoked),
      })
    }
  })

  return {
    upsertSession(meta) {
      upsertStmt.run({
        ...meta,
        tools_used: JSON.stringify(meta.tools_used),
        skills_invoked: JSON.stringify(meta.skills_invoked),
      })
    },
    upsertMany(metas) {
      upsertManyTxn(metas)
    },
    listSessions(filters) {
      const { sql, params } = buildWhere(filters)
      const limit = filters.limit ?? 50
      const offset = filters.offset ?? 0
      const rows = db
        .prepare(`SELECT * FROM sessions ${sql} ORDER BY started_at DESC LIMIT @limit OFFSET @offset`)
        .all({ ...params, limit, offset }) as Record<string, unknown>[]
      return rows.map(rowToMeta)
    },
    countSessions(filters) {
      const { sql, params } = buildWhere(filters)
      const row = db.prepare(`SELECT COUNT(*) as c FROM sessions ${sql}`).get(params) as { c: number }
      return row.c
    },
    getSession(id) {
      const row = db.prepare('SELECT * FROM sessions WHERE session_id = ?').get(id) as Record<string, unknown> | undefined
      return row ? rowToMeta(row) : null
    },
    deleteByJsonlPath(path) {
      db.prepare('DELETE FROM sessions WHERE jsonl_path = ?').run(path)
    },
    upsertPattern(p: PatternRecord) {
      db.prepare(`
        INSERT INTO patterns (detected_at, week_iso, pattern_key, title, description,
          severity, metric_value, sample_session_ids, affected_count, consecutive_weeks)
        VALUES (@detected_at, @week_iso, @pattern_key, @title, @description,
          @severity, @metric_value, @sample_session_ids, @affected_count, @consecutive_weeks)
        ON CONFLICT(week_iso, pattern_key) DO UPDATE SET
          detected_at = excluded.detected_at,
          title = excluded.title,
          description = excluded.description,
          severity = excluded.severity,
          metric_value = excluded.metric_value,
          sample_session_ids = excluded.sample_session_ids,
          affected_count = excluded.affected_count,
          consecutive_weeks = excluded.consecutive_weeks
      `).run({
        detected_at: p.detected_at,
        week_iso: p.week_iso,
        pattern_key: p.pattern_key,
        title: p.title,
        description: p.description,
        severity: p.severity,
        metric_value: p.metric_value,
        sample_session_ids: JSON.stringify(p.sample_session_ids),
        affected_count: p.affected_count,
        consecutive_weeks: p.consecutive_weeks,
      })
    },
    getPatternsByWeek(week: string): PatternRecord[] {
      const rows = db.prepare('SELECT * FROM patterns WHERE week_iso = ? ORDER BY severity DESC, affected_count DESC').all(week) as Record<string, unknown>[]
      return rows.map((r) => ({
        id: r.id as number,
        detected_at: r.detected_at as string,
        week_iso: r.week_iso as string,
        pattern_key: r.pattern_key as string,
        title: r.title as string,
        description: r.description as string,
        severity: r.severity as PatternRecord['severity'],
        metric_value: (r.metric_value as number | null) ?? null,
        sample_session_ids: JSON.parse(r.sample_session_ids as string),
        affected_count: r.affected_count as number,
        consecutive_weeks: r.consecutive_weeks as number,
      }))
    },
    getConsecutiveWeeks(pattern_key: string, uptoWeek: string): number {
      // Conta semanas consecutivas até uptoWeek (inclusive) em que pattern_key apareceu
      const rows = db.prepare('SELECT DISTINCT week_iso FROM patterns WHERE pattern_key = ? AND week_iso <= ? ORDER BY week_iso DESC').all(pattern_key, uptoWeek) as { week_iso: string }[]
      if (rows.length === 0) return 0
      let count = 0
      let cursor = uptoWeek
      for (const row of rows) {
        if (row.week_iso === cursor) {
          count++
          cursor = prevWeekIso(cursor)
        } else {
          break
        }
      }
      return count
    },
    upsertWorklogComment(c: WorklogCommentRecord): { inserted: boolean } {
      const existing = db.prepare('SELECT 1 FROM worklog_comments WHERE id = ?').get(c.id)
      const inserted = !existing
      db.prepare(`
        INSERT INTO worklog_comments (id, discussion_id, created_at, staff_id, title, task_ref,
          duration_sec, work_items, files_modified, problems_json, patterns_text, actions_json,
          raw_html, imported_at)
        VALUES (@id, @discussion_id, @created_at, @staff_id, @title, @task_ref,
          @duration_sec, @work_items, @files_modified, @problems_json, @patterns_text, @actions_json,
          @raw_html, @imported_at)
        ON CONFLICT(id) DO UPDATE SET
          discussion_id = excluded.discussion_id,
          created_at = excluded.created_at,
          staff_id = excluded.staff_id,
          title = excluded.title,
          task_ref = excluded.task_ref,
          duration_sec = excluded.duration_sec,
          work_items = excluded.work_items,
          files_modified = excluded.files_modified,
          problems_json = excluded.problems_json,
          patterns_text = excluded.patterns_text,
          actions_json = excluded.actions_json,
          raw_html = excluded.raw_html,
          imported_at = excluded.imported_at
      `).run({
        id: c.id,
        discussion_id: c.discussion_id,
        created_at: c.created_at,
        staff_id: c.staff_id,
        title: c.title,
        task_ref: c.task_ref,
        duration_sec: c.duration_sec,
        work_items: JSON.stringify(c.work_items),
        files_modified: JSON.stringify(c.files_modified),
        problems_json: JSON.stringify(c.problems),
        patterns_text: JSON.stringify(c.patterns_text),
        actions_json: JSON.stringify(c.actions),
        raw_html: c.raw_html,
        imported_at: c.imported_at,
      })
      return { inserted }
    },
    hasWorklogComment(id: number): boolean {
      return !!db.prepare('SELECT 1 FROM worklog_comments WHERE id = ?').get(id)
    },
    listWorklogComments(filters: WorklogFilters): WorklogCommentRecord[] {
      const parts: string[] = []
      const params: Record<string, unknown> = {}
      if (filters.discussion_id) { parts.push('discussion_id = @discussion_id'); params.discussion_id = filters.discussion_id }
      if (filters.task_ref) { parts.push('task_ref = @task_ref'); params.task_ref = filters.task_ref }
      if (filters.sinceIso) { parts.push('created_at >= @since'); params.since = filters.sinceIso }
      const where = parts.length ? 'WHERE ' + parts.join(' AND ') : ''
      const limit = filters.limit ?? 1000
      const offset = filters.offset ?? 0
      const rows = db.prepare(`SELECT * FROM worklog_comments ${where} ORDER BY created_at DESC LIMIT @limit OFFSET @offset`)
        .all({ ...params, limit, offset }) as Record<string, unknown>[]
      return rows.map((r) => ({
        id: r.id as number,
        discussion_id: r.discussion_id as number,
        created_at: r.created_at as string,
        staff_id: (r.staff_id as number | null) ?? null,
        title: (r.title as string | null) ?? null,
        task_ref: (r.task_ref as string | null) ?? null,
        duration_sec: (r.duration_sec as number | null) ?? null,
        work_items: JSON.parse(r.work_items as string),
        files_modified: JSON.parse(r.files_modified as string),
        problems: JSON.parse(r.problems_json as string),
        patterns_text: JSON.parse(r.patterns_text as string),
        actions: JSON.parse(r.actions_json as string),
        raw_html: r.raw_html as string,
        imported_at: r.imported_at as string,
      }))
    },
    countWorklogComments(filters?: WorklogFilters): number {
      const parts: string[] = []
      const params: Record<string, unknown> = {}
      if (filters?.discussion_id) { parts.push('discussion_id = @discussion_id'); params.discussion_id = filters.discussion_id }
      if (filters?.task_ref) { parts.push('task_ref = @task_ref'); params.task_ref = filters.task_ref }
      if (filters?.sinceIso) { parts.push('created_at >= @since'); params.since = filters.sinceIso }
      const where = parts.length ? 'WHERE ' + parts.join(' AND ') : ''
      const row = db.prepare(`SELECT COUNT(*) as c FROM worklog_comments ${where}`).get(params) as { c: number }
      return row.c
    },
    rawDb(): Database.Database {
      return db
    },
    close() {
      db.close()
    },
  }
}

/** Calcula semana ISO anterior (YYYY-Www). */
export function prevWeekIso(week: string): string {
  const m = week.match(/^(\d{4})-W(\d{2})$/)
  if (!m) return week
  const year = parseInt(m[1], 10)
  const w = parseInt(m[2], 10)
  if (w > 1) return `${year}-W${String(w - 1).padStart(2, '0')}`
  // Semana 1 → última semana do ano anterior (52 ou 53)
  const prevYear = year - 1
  const last = weeksInYear(prevYear)
  return `${prevYear}-W${String(last).padStart(2, '0')}`
}

function weeksInYear(year: number): number {
  // ISO: ano tem 53 semanas se 1 Jan é quinta ou (ano bissexto e 1 Jan é quarta)
  const jan1 = new Date(Date.UTC(year, 0, 1)).getUTCDay()
  const isLeap = (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0
  if (jan1 === 4 || (isLeap && jan1 === 3)) return 53
  return 52
}