package sqlite

import (
	"fmt"
	"strings"

	"git.warky.dev/wdevs/relspecgo/pkg/models"
)

// queryTables retrieves all tables from the SQLite database
func (r *Reader) queryTables() ([]*models.Table, error) {
	query := `
		SELECT name
		FROM sqlite_master
		WHERE type = 'table'
		  AND name NOT LIKE 'sqlite_%'
		ORDER BY name
	`

	rows, err := r.db.QueryContext(r.ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	tables := make([]*models.Table, 0)
	for rows.Next() {
		var tableName string

		if err := rows.Scan(&tableName); err != nil {
			return nil, err
		}

		table := models.InitTable(tableName, "main")
		tables = append(tables, table)
	}

	return tables, rows.Err()
}

// queryViews retrieves all views from the SQLite database
func (r *Reader) queryViews() ([]*models.View, error) {
	query := `
		SELECT name, sql
		FROM sqlite_master
		WHERE type = 'view'
		ORDER BY name
	`

	rows, err := r.db.QueryContext(r.ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	views := make([]*models.View, 0)
	for rows.Next() {
		var viewName string
		var sql *string

		if err := rows.Scan(&viewName, &sql); err != nil {
			return nil, err
		}

		view := models.InitView(viewName, "main")
		if sql != nil {
			view.Definition = *sql
		}

		views = append(views, view)
	}

	return views, rows.Err()
}

// queryColumns retrieves all columns for a given table or view
func (r *Reader) queryColumns(tableName string) (map[string]*models.Column, error) {
	query := fmt.Sprintf("PRAGMA table_info(%s)", tableName)

	rows, err := r.db.QueryContext(r.ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	columns := make(map[string]*models.Column)

	for rows.Next() {
		var cid int
		var name, dataType string
		var notNull, pk int
		var defaultValue *string

		if err := rows.Scan(&cid, &name, &dataType, &notNull, &defaultValue, &pk); err != nil {
			return nil, err
		}

		column := models.InitColumn(name, tableName, "main")
		column.Type = r.mapDataType(strings.ToUpper(dataType))
		column.NotNull = (notNull == 1)
		column.IsPrimaryKey = (pk > 0)
		column.Sequence = uint(cid + 1)

		if defaultValue != nil {
			column.Default = *defaultValue
		}

		// Check for autoincrement (SQLite uses INTEGER PRIMARY KEY AUTOINCREMENT)
		if pk > 0 && strings.ToUpper(dataType) == "INTEGER" {
			column.AutoIncrement = r.isAutoIncrement(tableName, name)
		}

		columns[name] = column
	}

	return columns, rows.Err()
}

// isAutoIncrement checks if a column is autoincrement
func (r *Reader) isAutoIncrement(tableName, columnName string) bool {
	// Check sqlite_sequence table or parse CREATE TABLE statement
	query := `
		SELECT sql
		FROM sqlite_master
		WHERE type = 'table' AND name = ?
	`

	var sql string
	err := r.db.QueryRowContext(r.ctx, query, tableName).Scan(&sql)
	if err != nil {
		return false
	}

	// Check if the SQL contains AUTOINCREMENT for this column
	return strings.Contains(strings.ToUpper(sql), strings.ToUpper(columnName)+" INTEGER PRIMARY KEY AUTOINCREMENT") ||
		strings.Contains(strings.ToUpper(sql), strings.ToUpper(columnName)+" INTEGER AUTOINCREMENT")
}

// queryPrimaryKey retrieves the primary key constraint for a table
func (r *Reader) queryPrimaryKey(tableName string) (*models.Constraint, error) {
	query := fmt.Sprintf("PRAGMA table_info(%s)", tableName)

	rows, err := r.db.QueryContext(r.ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var pkColumns []string

	for rows.Next() {
		var cid int
		var name, dataType string
		var notNull, pk int
		var defaultValue *string

		if err := rows.Scan(&cid, &name, &dataType, &notNull, &defaultValue, &pk); err != nil {
			return nil, err
		}

		if pk > 0 {
			pkColumns = append(pkColumns, name)
		}
	}

	if len(pkColumns) == 0 {
		return nil, nil
	}

	// Create primary key constraint
	constraintName := fmt.Sprintf("%s_pkey", tableName)
	constraint := models.InitConstraint(constraintName, models.PrimaryKeyConstraint)
	constraint.Schema = "main"
	constraint.Table = tableName
	constraint.Columns = pkColumns

	return constraint, rows.Err()
}

// queryForeignKeys retrieves all foreign key constraints for a table
func (r *Reader) queryForeignKeys(tableName string) ([]*models.Constraint, error) {
	query := fmt.Sprintf("PRAGMA foreign_key_list(%s)", tableName)

	rows, err := r.db.QueryContext(r.ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	// Group foreign keys by id (since composite FKs have multiple rows)
	fkMap := make(map[int]*models.Constraint)

	for rows.Next() {
		var id, seq int
		var referencedTable, fromColumn, toColumn string
		var onUpdate, onDelete, match string

		if err := rows.Scan(&id, &seq, &referencedTable, &fromColumn, &toColumn, &onUpdate, &onDelete, &match); err != nil {
			return nil, err
		}

		if _, exists := fkMap[id]; !exists {
			constraintName := fmt.Sprintf("%s_%s_fkey", tableName, referencedTable)
			if id > 0 {
				constraintName = fmt.Sprintf("%s_%s_fkey_%d", tableName, referencedTable, id)
			}

			constraint := models.InitConstraint(constraintName, models.ForeignKeyConstraint)
			constraint.Schema = "main"
			constraint.Table = tableName
			constraint.ReferencedSchema = "main"
			constraint.ReferencedTable = referencedTable
			constraint.OnUpdate = onUpdate
			constraint.OnDelete = onDelete
			constraint.Columns = []string{}
			constraint.ReferencedColumns = []string{}

			fkMap[id] = constraint
		}

		// Add column to the constraint
		fkMap[id].Columns = append(fkMap[id].Columns, fromColumn)
		fkMap[id].ReferencedColumns = append(fkMap[id].ReferencedColumns, toColumn)
	}

	// Convert map to slice
	foreignKeys := make([]*models.Constraint, 0, len(fkMap))
	for _, fk := range fkMap {
		foreignKeys = append(foreignKeys, fk)
	}

	return foreignKeys, rows.Err()
}

// queryIndexes retrieves all indexes for a table
func (r *Reader) queryIndexes(tableName string) ([]*models.Index, error) {
	query := fmt.Sprintf("PRAGMA index_list(%s)", tableName)

	rows, err := r.db.QueryContext(r.ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	indexes := make([]*models.Index, 0)

	for rows.Next() {
		var seq int
		var name string
		var unique int
		var origin string
		var partial int

		if err := rows.Scan(&seq, &name, &unique, &origin, &partial); err != nil {
			return nil, err
		}

		// Skip auto-generated indexes (origin = 'pk' for primary keys, etc.)
		// origin: c = CREATE INDEX, u = UNIQUE constraint, pk = PRIMARY KEY
		if origin == "pk" || origin == "u" {
			continue
		}

		index := models.InitIndex(name, tableName, "main")
		index.Unique = (unique == 1)

		// Get index columns
		columns, err := r.queryIndexColumns(name)
		if err != nil {
			return nil, err
		}
		index.Columns = columns

		indexes = append(indexes, index)
	}

	return indexes, rows.Err()
}

// queryIndexColumns retrieves the columns for a specific index
func (r *Reader) queryIndexColumns(indexName string) ([]string, error) {
	query := fmt.Sprintf("PRAGMA index_info(%s)", indexName)

	rows, err := r.db.QueryContext(r.ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	columns := make([]string, 0)

	for rows.Next() {
		var seqno, cid int
		var name *string

		if err := rows.Scan(&seqno, &cid, &name); err != nil {
			return nil, err
		}

		if name != nil {
			columns = append(columns, *name)
		}
	}

	return columns, rows.Err()
}