export function useMigrations() {
  const CURRENT_SCHEMA_VERSION = "1.1"
  const SCHEMA_KEY = "urgent-tools-schema-version"

  // Get stored schema version
  function getStoredVersion(): string {
    if (process.client) {
      return localStorage.getItem(SCHEMA_KEY) || "1.0"
    }
    return "1.0"
  }

  // Set schema version
  function setVersion(version: string) {
    if (process.client) {
      localStorage.setItem(SCHEMA_KEY, version)
    }
  }

  // Migration functions
  const migrations = {
    "1.0": () => {
      // Initial schema - no migration needed
    },
    
    "1.1": () => {
      // Add new member needs fields
      const membersData = localStorage.getItem("urgent-tools-members")
      if (membersData) {
        try {
          const parsed = JSON.parse(membersData)
          if (Array.isArray(parsed.members)) {
            // Add default values for new fields
            parsed.members = parsed.members.map((member: any) => ({
              ...member,
              minMonthlyNeeds: member.minMonthlyNeeds || 0,
              targetMonthlyPay: member.targetMonthlyPay || 0,
              externalMonthlyIncome: member.externalMonthlyIncome || 0,
              monthlyPayPlanned: member.monthlyPayPlanned || 0,
            }))
            localStorage.setItem("urgent-tools-members", JSON.stringify(parsed))
          }
        } catch (error) {
          console.warn("Failed to migrate members data:", error)
        }
      }

      // Add new policy fields
      const policiesData = localStorage.getItem("urgent-tools-policies")
      if (policiesData) {
        try {
          const parsed = JSON.parse(policiesData)
          parsed.operatingMode = parsed.operatingMode || 'minimum'
          parsed.payPolicy = parsed.payPolicy || { 
            relationship: 'equal-pay', 
            roleBands: [] 
          }
          localStorage.setItem("urgent-tools-policies", JSON.stringify(parsed))
        } catch (error) {
          console.warn("Failed to migrate policies data:", error)
        }
      }

      // DISABLED: No automatic cash balance initialization
      // The app should start completely empty - no demo data
      // 
      // Previously this would auto-initialize cash balances, but this
      // created unwanted demo data. Users must explicitly set up their data.
      //
      // const cashData = localStorage.getItem("urgent-tools-cash")
      // if (!cashData) {
      //   localStorage.setItem("urgent-tools-cash", JSON.stringify({
      //     currentCash: 50000,
      //     currentSavings: 15000,
      //     cashEvents: [],
      //     paymentQueue: []
      //   }))
      // }
    }
  }

  // Run all necessary migrations
  function migrate() {
    if (!process.client) return

    const currentVersion = getStoredVersion()
    
    if (currentVersion === CURRENT_SCHEMA_VERSION) {
      return // Already up to date
    }

    console.log(`Migrating from schema version ${currentVersion} to ${CURRENT_SCHEMA_VERSION}`)

    // Run migrations in order
    const versions = Object.keys(migrations).sort()
    const currentIndex = versions.indexOf(currentVersion)
    
    if (currentIndex === -1) {
      console.warn(`Unknown schema version: ${currentVersion}, running all migrations`)
      // Run all migrations
      versions.forEach(version => {
        try {
          migrations[version as keyof typeof migrations]()
          console.log(`Applied migration: ${version}`)
        } catch (error) {
          console.error(`Migration ${version} failed:`, error)
        }
      })
    } else {
      // Run migrations from current version + 1 to latest
      for (let i = currentIndex + 1; i < versions.length; i++) {
        const version = versions[i]
        try {
          migrations[version as keyof typeof migrations]()
          console.log(`Applied migration: ${version}`)
        } catch (error) {
          console.error(`Migration ${version} failed:`, error)
        }
      }
    }

    // Update stored version
    setVersion(CURRENT_SCHEMA_VERSION)
    console.log(`Migration complete. Schema version: ${CURRENT_SCHEMA_VERSION}`)
  }

  // Check if migration is needed
  function needsMigration(): boolean {
    // Don't run migrations if data was intentionally cleared
    if (process.client && localStorage.getItem('urgent-tools-cleared-flag') === 'true') {
      return false
    }
    return getStoredVersion() !== CURRENT_SCHEMA_VERSION
  }

  return {
    migrate,
    needsMigration,
    currentVersion: CURRENT_SCHEMA_VERSION,
    storedVersion: getStoredVersion()
  }
}