import { beforeEach, afterEach, describe, expect, it, vi } from "vitest"

import {
  FLAG_DEFAULTS,
  Flags,
  getFlags,
  registerRuntimeFlags,
  resetFlagsCache,
  parseBool,
} from "@/lib/flags"

type FlagName = keyof typeof FLAG_DEFAULTS
const flagKeys = Object.keys(FLAG_DEFAULTS) as FlagName[]

const originalEnv: Partial<Record<FlagName, string | undefined>> = {}

beforeEach(() => {
  resetFlagsCache()
  for (const key of flagKeys) {
    if (!(key in originalEnv)) {
      originalEnv[key] = process.env[key]
    }
    delete process.env[key]
  }
  delete (globalThis as Record<string, unknown>).__MULTI_AGENT_CHAT_FLAGS__
})

afterEach(() => {
  resetFlagsCache()
  for (const key of flagKeys) {
    const value = originalEnv[key]
    if (value === undefined) {
      delete process.env[key]
    } else {
      process.env[key] = value
    }
  }
  delete (globalThis as Record<string, unknown>).__MULTI_AGENT_CHAT_FLAGS__
})

describe("parseBool", () => {
  it("handles string coercion and defaults", () => {
    expect(parseBool("true", false)).toBe(true)
    expect(parseBool(" FALSE ", true)).toBe(false)
    expect(parseBool("1", false)).toBe(true)
    expect(parseBool("0", true)).toBe(false)
    expect(parseBool(undefined, true)).toBe(true)
    expect(parseBool(undefined, false)).toBe(false)
  })

  it("handles yes/no values", () => {
    expect(parseBool("yes", false)).toBe(true)
    expect(parseBool("YES", false)).toBe(true)
    expect(parseBool("no", true)).toBe(false)
    expect(parseBool("NO", true)).toBe(false)
  })

  it("uses default for invalid values", () => {
    expect(parseBool("invalid", true)).toBe(true)
    expect(parseBool("maybe", false)).toBe(false)
  })
})

describe("getFlags", () => {
  it("returns default values when no environment variables are set", () => {
    const snapshot = getFlags({ refresh: true })

    expect(snapshot).toMatchObject(FLAG_DEFAULTS)
    expect(snapshot.IMAGE_UPLOADS_ENABLED).toBe(true)
    expect(snapshot.DIFF_TOOL_ENABLED).toBe(true)
  })

  it("honours environment overrides", () => {
    process.env.IMAGE_UPLOADS_ENABLED = "false"
    process.env.DIFF_TOOL_ENABLED = "true"

    const snapshot = getFlags({ refresh: true })

    expect(snapshot.IMAGE_UPLOADS_ENABLED).toBe(false)
    expect(snapshot.DIFF_TOOL_ENABLED).toBe(true)
  })

  it("caches flags by default", () => {
    const snapshot1 = getFlags()
    process.env.IMAGE_UPLOADS_ENABLED = "false"

    const snapshot2 = getFlags()
    expect(snapshot2.IMAGE_UPLOADS_ENABLED).toBe(true) // Still cached
  })

  it("refreshes cache when requested", () => {
    const snapshot1 = getFlags()
    process.env.IMAGE_UPLOADS_ENABLED = "false"

    const snapshot2 = getFlags({ refresh: true })
    expect(snapshot2.IMAGE_UPLOADS_ENABLED).toBe(false) // Refreshed
  })
})

describe("registerRuntimeFlags", () => {
  it("allows runtime overrides to take precedence", () => {
    process.env.IMAGE_UPLOADS_ENABLED = "true"
    const override = { IMAGE_UPLOADS_ENABLED: false }

    registerRuntimeFlags(override)
    const snapshot = getFlags()

    expect(snapshot.IMAGE_UPLOADS_ENABLED).toBe(false)
  })

  it("supports partial overrides", () => {
    registerRuntimeFlags({ DIFF_TOOL_ENABLED: false })
    const snapshot = getFlags()

    expect(snapshot.IMAGE_UPLOADS_ENABLED).toBe(true) // Default
    expect(snapshot.DIFF_TOOL_ENABLED).toBe(false) // Overridden
  })
})

describe("Flags proxy", () => {
  it("reflects current snapshot values", () => {
    process.env.IMAGE_UPLOADS_ENABLED = "false"
    const snapshot = getFlags({ refresh: true })

    expect(snapshot.IMAGE_UPLOADS_ENABLED).toBe(false)
    expect(Flags.IMAGE_UPLOADS_ENABLED).toBe(false)
  })

  it("reflects runtime overrides", () => {
    registerRuntimeFlags({ DIFF_TOOL_ENABLED: false })

    expect(Flags.DIFF_TOOL_ENABLED).toBe(false)
  })
})