import { uuidv7 } from '@sims/domain'
import { writeAudit } from './audit'
import type { DB } from './db'

/**
 * Onboarding tracker (D22). Each client_module (a "project") carries a checklist of
 * milestones — advance paid, setup, install, go-live, balance, AMC — seeded from the
 * dated `project.milestone_template` setting. Ticking one stamps the date. Reportable
 * across the whole book: "who's pending go-live", "who hasn't paid the advance".
 */

export interface Milestone { key: string; label: string; done: boolean; doneOn: string | null; sort: number }
interface MilestoneRow { key: string; label: string; done: number; done_on: string | null; sort: number }

interface TemplateEntry { key: string; label: string }

const FALLBACK_TEMPLATE: TemplateEntry[] = [
  { key: 'advance_paid', label: 'Advance payment received' },
  { key: 'setup_done', label: 'Setup / configuration done' },
  { key: 'installed', label: 'Installation done' },
  { key: 'go_live', label: 'Go-live' },
  { key: 'balance_paid', label: 'Balance payment received' },
  { key: 'amc_start', label: 'AMC / renewal start' },
]

/** The standard checklist (owner-editable via the setting; fallback to the code default). */
export async function milestoneTemplate(db: DB): Promise<TemplateEntry[]> {
  const row = await db.get<{ value: string }>(`SELECT value FROM setting WHERE key='project.milestone_template'`)
  if (row === undefined) return FALLBACK_TEMPLATE
  try {
    const parsed = JSON.parse(row.value) as TemplateEntry[]
    return Array.isArray(parsed) && parsed.length > 0 ? parsed : FALLBACK_TEMPLATE
  } catch { return FALLBACK_TEMPLATE }
}

/**
 * Idempotently materialize the template's milestones for a project. New template rows are
 * added on later calls (so extending the standard set reaches existing projects); a
 * project's own custom milestones and any ticked state are never touched.
 */
export async function ensureProjectMilestones(db: DB, clientModuleId: string): Promise<void> {
  const template = await milestoneTemplate(db)
  const existing = new Set(
    (await db.all<{ key: string }>(`SELECT key FROM project_milestone WHERE client_module_id=?`, clientModuleId))
      .map((r) => r.key),
  )
  await db.transaction(async () => {
    let sort = 0
    for (const t of template) {
      if (!existing.has(t.key)) {
        await db.run(
          `INSERT INTO project_milestone (id, client_module_id, key, label, done, done_on, sort)
           VALUES (?, ?, ?, ?, 0, NULL, ?)`,
          uuidv7(), clientModuleId, t.key, t.label, sort,
        )
      }
      sort++
    }
  })
}

export async function listProjectMilestones(db: DB, clientModuleId: string): Promise<Milestone[]> {
  const rows = await db.all<MilestoneRow>(
    `SELECT key, label, done, done_on, sort FROM project_milestone
     WHERE client_module_id=? ORDER BY sort, label`,
    clientModuleId,
  )
  return rows.map((r) => ({ key: r.key, label: r.label, done: r.done === 1, doneOn: r.done_on, sort: r.sort }))
}

/** Tick / untick a milestone. Ticking stamps done_on (given date or today); unticking clears it. Audited. */
export async function setMilestone(
  db: DB, userId: string, clientModuleId: string, key: string, done: boolean, doneOn?: string,
): Promise<Milestone[]> {
  return db.transaction(async () => {
    const before = await db.get<MilestoneRow>(
      `SELECT key, label, done, done_on, sort FROM project_milestone WHERE client_module_id=? AND key=?`,
      clientModuleId, key,
    )
    if (before === undefined) throw new Error('Milestone not found on this project')
    if (done && doneOn !== undefined && !/^\d{4}-\d{2}-\d{2}$/.test(doneOn)) {
      throw new Error('doneOn must be YYYY-MM-DD')
    }
    const stamp = done ? (doneOn ?? new Date().toISOString().slice(0, 10)) : null
    await db.run(
      `UPDATE project_milestone SET done=?, done_on=? WHERE client_module_id=? AND key=?`,
      done ? 1 : 0, stamp, clientModuleId, key,
    )
    await writeAudit(db, userId, 'set_milestone', 'client_module', clientModuleId, undefined, { key, done, doneOn: stamp })
    return listProjectMilestones(db, clientModuleId)
  })
}

/** Add a project-specific milestone (beyond the standard template). Audited. */
export async function addProjectMilestone(
  db: DB, userId: string, clientModuleId: string, label: string,
): Promise<Milestone[]> {
  return db.transaction(async () => {
    if (label.trim() === '') throw new Error('Milestone label is required')
    const key = `custom_${uuidv7().slice(0, 8)}`
    const maxSort = (await db.get<{ m: number }>(
      `SELECT COALESCE(MAX(sort), -1) AS m FROM project_milestone WHERE client_module_id=?`, clientModuleId,
    ))!.m
    await db.run(
      `INSERT INTO project_milestone (id, client_module_id, key, label, done, done_on, sort)
       VALUES (?, ?, ?, ?, 0, NULL, ?)`,
      uuidv7(), clientModuleId, key, label.trim(), maxSort + 1,
    )
    await writeAudit(db, userId, 'add_milestone', 'client_module', clientModuleId, undefined, { key, label: label.trim() })
    return listProjectMilestones(db, clientModuleId)
  })
}

// ---------- cross-project reporting (the board) ----------

export interface MilestoneBoardRow { key: string; label: string; total: number; done: number; pending: number }

/**
 * Per-milestone completion across ALL active projects — the onboarding board. Ordered by
 * the standard template; ad-hoc custom milestones are aggregated too, after the standard set.
 */
export async function milestoneBoard(db: DB): Promise<MilestoneBoardRow[]> {
  const rows = await db.all<{ key: string; label: string; total: number; done: number; minsort: number }>(
    `SELECT pm.key, MIN(pm.label) AS label,
            COUNT(*) AS total,
            COALESCE(SUM(pm.done), 0) AS done,
            MIN(pm.sort) AS minsort
     FROM project_milestone pm
     JOIN client_module cm ON cm.id = pm.client_module_id
     WHERE cm.active = 1
     GROUP BY pm.key
     ORDER BY minsort, label`,
  )
  return rows.map((r) => ({ key: r.key, label: r.label, total: r.total, done: r.done, pending: r.total - r.done }))
}

export interface PendingProject {
  clientModuleId: string; clientId: string; clientName: string; moduleCode: string; moduleName: string
}

/** Active projects where the given milestone is NOT yet done — the drill-down. */
export async function projectsPendingMilestone(db: DB, key: string): Promise<PendingProject[]> {
  return db.all<PendingProject>(
    `SELECT pm.client_module_id AS "clientModuleId", cm.client_id AS "clientId",
            c.name AS "clientName", m.code AS "moduleCode", m.name AS "moduleName"
     FROM project_milestone pm
     JOIN client_module cm ON cm.id = pm.client_module_id
     JOIN client c ON c.id = cm.client_id
     JOIN module m ON m.id = cm.module_id
     WHERE cm.active = 1 AND pm.key = ? AND pm.done = 0
     ORDER BY c.name`,
    key,
  )
}