package server

import (
	"encoding/csv"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"strconv"
	"strings"
	"time"

	"odoo-go/pkg/orm"
)

// handleBankStatementImport imports bank statement lines from CSV data.
// Accepts JSON body with: journal_id, csv_data, column_mapping, has_header.
// After import, optionally triggers auto-matching against open invoices.
// Mirrors: odoo/addons/account/wizard/account_bank_statement_import.py
func (s *Server) handleBankStatementImport(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req JSONRPCRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		s.writeJSONRPC(w, nil, nil, &RPCError{Code: -32700, Message: "Parse error"})
		return
	}

	var params struct {
		JournalID     int64             `json:"journal_id"`
		CSVData       string            `json:"csv_data"`
		HasHeader     bool              `json:"has_header"`
		ColumnMapping bankColumnMapping `json:"column_mapping"`
		AutoMatch     bool              `json:"auto_match"`
	}
	if err := json.Unmarshal(req.Params, &params); err != nil {
		s.writeJSONRPC(w, req.ID, nil, &RPCError{Code: -32602, Message: "Invalid params"})
		return
	}

	if params.JournalID == 0 || params.CSVData == "" {
		s.writeJSONRPC(w, req.ID, nil, &RPCError{Code: -32602, Message: "journal_id and csv_data are required"})
		return
	}

	uid := int64(1)
	companyID := int64(1)
	if sess := GetSession(r); sess != nil {
		uid = sess.UID
		companyID = sess.CompanyID
	}

	env, err := orm.NewEnvironment(r.Context(), orm.EnvConfig{
		Pool:      s.pool,
		UID:       uid,
		CompanyID: companyID,
	})
	if err != nil {
		s.writeJSONRPC(w, req.ID, nil, &RPCError{Code: -32603, Message: "Internal error"})
		return
	}
	defer env.Close()

	// Parse CSV
	reader := csv.NewReader(strings.NewReader(params.CSVData))
	reader.LazyQuotes = true
	reader.TrimLeadingSpace = true
	// Try semicolon separator (common in European bank exports)
	reader.Comma = detectDelimiter(params.CSVData)

	var allRows [][]string
	for {
		row, err := reader.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			s.writeJSONRPC(w, req.ID, nil, &RPCError{Code: -32602, Message: fmt.Sprintf("CSV parse error: %v", err)})
			return
		}
		allRows = append(allRows, row)
	}

	dataRows := allRows
	if params.HasHeader && len(allRows) > 1 {
		dataRows = allRows[1:]
	}

	// Create a bank statement header
	statementRS := env.Model("account.bank.statement")
	stmt, err := statementRS.Create(orm.Values{
		"name":       fmt.Sprintf("Import %s", time.Now().Format("2006-01-02 15:04")),
		"journal_id": params.JournalID,
		"company_id": companyID,
		"date":       time.Now().Format("2006-01-02"),
	})
	if err != nil {
		s.writeJSONRPC(w, req.ID, nil, &RPCError{Code: -32603, Message: fmt.Sprintf("Create statement: %v", err)})
		return
	}
	stmtID := stmt.ID()

	// Default column mapping
	cm := params.ColumnMapping
	if cm.Date < 0 {
		cm.Date = 0
	}
	if cm.Amount < 0 {
		cm.Amount = 1
	}
	if cm.Label < 0 {
		cm.Label = 2
	}

	// Import lines
	lineRS := env.Model("account.bank.statement.line")
	var importedIDs []int64
	var errors []importError

	for rowIdx, row := range dataRows {
		// Parse date
		dateStr := safeCol(row, cm.Date)
		date := parseFlexDate(dateStr)
		if date == "" {
			date = time.Now().Format("2006-01-02")
		}

		// Parse amount
		amountStr := safeCol(row, cm.Amount)
		amount := parseAmount(amountStr)
		if amount == 0 {
			continue // skip zero-amount rows
		}

		// Parse label/reference
		label := safeCol(row, cm.Label)
		if label == "" {
			label = fmt.Sprintf("Line %d", rowIdx+1)
		}

		// Parse optional columns
		partnerName := safeCol(row, cm.PartnerName)
		accountNumber := safeCol(row, cm.AccountNumber)

		vals := orm.Values{
			"statement_id":   stmtID,
			"journal_id":     params.JournalID,
			"company_id":     companyID,
			"date":           date,
			"amount":         amount,
			"payment_ref":    label,
			"partner_name":   partnerName,
			"account_number": accountNumber,
			"sequence":       rowIdx + 1,
		}

		rec, err := lineRS.Create(vals)
		if err != nil {
			errors = append(errors, importError{Row: rowIdx + 1, Message: err.Error()})
			log.Printf("bank_import: row %d error: %v", rowIdx+1, err)
			continue
		}
		importedIDs = append(importedIDs, rec.ID())
	}

	// Auto-match against open invoices
	matchCount := 0
	if params.AutoMatch && len(importedIDs) > 0 {
		stLineModel := orm.Registry.Get("account.bank.statement.line")
		if stLineModel != nil {
			if matchMethod, ok := stLineModel.Methods["button_match"]; ok {
				matchRS := env.Model("account.bank.statement.line").Browse(importedIDs...)
				if _, err := matchMethod(matchRS); err != nil {
					log.Printf("bank_import: auto-match error: %v", err)
				}
			}
		}
		// Count how many were matched
		env.Tx().QueryRow(env.Ctx(),
			`SELECT COUNT(*) FROM account_bank_statement_line WHERE id = ANY($1) AND is_reconciled = true`,
			importedIDs).Scan(&matchCount)
	}

	if err := env.Commit(); err != nil {
		s.writeJSONRPC(w, req.ID, nil, &RPCError{Code: -32603, Message: fmt.Sprintf("Commit: %v", err)})
		return
	}

	s.writeJSONRPC(w, req.ID, map[string]interface{}{
		"statement_id": stmtID,
		"imported":     len(importedIDs),
		"matched":      matchCount,
		"errors":       errors,
	}, nil)
}

// bankColumnMapping maps CSV columns to bank statement fields.
type bankColumnMapping struct {
	Date          int `json:"date"`           // column index for date
	Amount        int `json:"amount"`         // column index for amount
	Label         int `json:"label"`          // column index for label/reference
	PartnerName   int `json:"partner_name"`   // column index for partner name (-1 = skip)
	AccountNumber int `json:"account_number"` // column index for account number (-1 = skip)
}

// detectDelimiter guesses the CSV delimiter (comma, semicolon, or tab).
func detectDelimiter(data string) rune {
	firstLine := data
	if idx := strings.IndexByte(data, '\n'); idx > 0 {
		firstLine = data[:idx]
	}
	semicolons := strings.Count(firstLine, ";")
	commas := strings.Count(firstLine, ",")
	tabs := strings.Count(firstLine, "\t")

	if semicolons > commas && semicolons > tabs {
		return ';'
	}
	if tabs > commas {
		return '\t'
	}
	return ','
}

// safeCol returns the value at index i, or "" if out of bounds.
func safeCol(row []string, i int) string {
	if i < 0 || i >= len(row) {
		return ""
	}
	return strings.TrimSpace(row[i])
}

// parseFlexDate tries multiple date formats and returns YYYY-MM-DD.
func parseFlexDate(s string) string {
	s = strings.TrimSpace(s)
	if s == "" {
		return ""
	}
	formats := []string{
		"2006-01-02",
		"02.01.2006",       // DD.MM.YYYY (common in EU)
		"01/02/2006",       // MM/DD/YYYY
		"02/01/2006",       // DD/MM/YYYY
		"2006/01/02",
		"Jan 2, 2006",
		"2 Jan 2006",
		"02-01-2006",
		"01-02-2006",
		time.RFC3339,
	}
	for _, f := range formats {
		if t, err := time.Parse(f, s); err == nil {
			return t.Format("2006-01-02")
		}
	}
	return ""
}

// parseAmount parses a monetary amount string, handling comma/dot decimals and negative formats.
func parseAmount(s string) float64 {
	s = strings.TrimSpace(s)
	if s == "" {
		return 0
	}
	// Remove currency symbols and whitespace
	s = strings.NewReplacer("€", "", "$", "", "£", "", " ", "", "\u00a0", "").Replace(s)

	// Handle European format: 1.234,56 → 1234.56
	if strings.Contains(s, ",") && strings.Contains(s, ".") {
		if strings.LastIndex(s, ",") > strings.LastIndex(s, ".") {
			// comma is decimal: 1.234,56
			s = strings.ReplaceAll(s, ".", "")
			s = strings.ReplaceAll(s, ",", ".")
		} else {
			// dot is decimal: 1,234.56
			s = strings.ReplaceAll(s, ",", "")
		}
	} else if strings.Contains(s, ",") {
		// Only comma: assume decimal separator
		s = strings.ReplaceAll(s, ",", ".")
	}

	v, err := strconv.ParseFloat(s, 64)
	if err != nil {
		return 0
	}
	return v
}