import { createClient } from "@/lib/supabase/client"
import type { KnowledgeItem, KnowledgeItemInput, Mastery } from "@/lib/types"

const TABLE = "knowledge_items"

export async function fetchItems(): Promise<KnowledgeItem[]> {
  const supabase = createClient()
  const { data, error } = await supabase.from(TABLE).select("*").order("created_at", { ascending: false })
  if (error) throw error
  return (data ?? []) as KnowledgeItem[]
}

export async function createItem(input: KnowledgeItemInput): Promise<KnowledgeItem> {
  const supabase = createClient()
  const { data, error } = await supabase
    .from(TABLE)
    .insert({ ...input })
    .select("*")
    .single()
  if (error) throw error
  return data as KnowledgeItem
}

export async function createItems(inputs: KnowledgeItemInput[]): Promise<KnowledgeItem[]> {
  const supabase = createClient()
  const { data, error } = await supabase
    .from(TABLE)
    .insert(inputs.map((i) => ({ ...i })))
    .select("*")
  if (error) throw error
  return (data ?? []) as KnowledgeItem[]
}

export async function updateItem(id: string, input: Partial<KnowledgeItemInput>): Promise<KnowledgeItem> {
  const supabase = createClient()
  const { data, error } = await supabase
    .from(TABLE)
    .update({ ...input, updated_at: new Date().toISOString() })
    .eq("id", id)
    .select("*")
    .single()
  if (error) throw error
  return data as KnowledgeItem
}

export async function saveInterviewAnswer(id: string, answer: string): Promise<void> {
  const supabase = createClient()
  const { error } = await supabase
    .from(TABLE)
    .update({ interview_answer: answer, updated_at: new Date().toISOString() })
    .eq("id", id)
  if (error) throw error
}

export async function deleteItem(id: string): Promise<void> {
  const supabase = createClient()
  const { error } = await supabase.from(TABLE).delete().eq("id", id)
  if (error) throw error
}

export async function toggleFavorite(id: string, value: boolean): Promise<void> {
  const supabase = createClient()
  const { error } = await supabase.from(TABLE).update({ is_favorite: value }).eq("id", id)
  if (error) throw error
}

export async function reviewItem(id: string, currentCount: number, mastery: Mastery): Promise<KnowledgeItem> {
  const supabase = createClient()
  const now = new Date()
  // simple spaced-repetition: schedule next review based on mastery
  const daysAhead = mastery === "mastered" ? 14 : mastery === "learning" ? 4 : 1
  const next = new Date(now.getTime() + daysAhead * 24 * 60 * 60 * 1000)
  const { data, error } = await supabase
    .from(TABLE)
    .update({
      review_count: currentCount + 1,
      last_reviewed_at: now.toISOString(),
      next_review_at: next.toISOString(),
    })
    .eq("id", id)
    .select("*")
    .single()
  if (error) throw error
  return data as KnowledgeItem
}