package lint

import (
	"fmt"

	pg_query "github.com/pganalyze/pg_query_go/v6"

	"git.warky.dev/wdevs/pgtidy/pkg/diagnostics"
	"git.warky.dev/wdevs/pgtidy/pkg/pgast"
)

// COR001 — SELECT *.
// Selecting all columns by wildcard is fragile: column additions/removals
// break callers silently. Enumerate the columns you need explicitly.
type ruleCOR001 struct{}

func (ruleCOR001) ID() string                     { return "COR001" }
func (ruleCOR001) Severity() diagnostics.Severity { return diagnostics.SeverityHint }

func (ruleCOR001) Check(stmts []*pg_query.RawStmt, src string) []diagnostics.Diagnostic {
	var out []diagnostics.Diagnostic
	for _, raw := range stmts {
		walkSelectStar(raw.Stmt, src, &out)
	}
	return out
}

func walkSelectStar(node *pg_query.Node, src string, out *[]diagnostics.Diagnostic) {
	if node == nil {
		return
	}
	sel, ok := node.GetNode().(*pg_query.Node_SelectStmt)
	if !ok {
		return
	}
	checkSelectStmt(sel.SelectStmt, src, out)
}

func checkSelectStmt(s *pg_query.SelectStmt, src string, out *[]diagnostics.Diagnostic) {
	if s == nil {
		return
	}
	for _, t := range s.TargetList {
		rt, ok := t.GetNode().(*pg_query.Node_ResTarget)
		if !ok {
			continue
		}
		cr, ok := rt.ResTarget.Val.GetNode().(*pg_query.Node_ColumnRef)
		if !ok {
			continue
		}
		for _, f := range cr.ColumnRef.Fields {
			if _, isStar := f.GetNode().(*pg_query.Node_AStar); isStar {
				line, col := pgast.LocationToLineCol(src, int(cr.ColumnRef.Location))
				*out = append(*out, diagnostics.Diagnostic{
					RuleID:   "COR001",
					Severity: diagnostics.SeverityHint,
					Message:  "SELECT * is fragile; enumerate the columns explicitly",
					Line:     line,
					Col:      col,
				})
			}
		}
	}
	// Recurse into set-operation branches (UNION, INTERSECT, EXCEPT).
	checkSelectStmt(s.Larg, src, out)
	checkSelectStmt(s.Rarg, src, out)
}

// COR002 — UPDATE without WHERE.
// An UPDATE with no WHERE clause modifies every row in the table.
type ruleCOR002 struct{}

func (ruleCOR002) ID() string                     { return "COR002" }
func (ruleCOR002) Severity() diagnostics.Severity { return diagnostics.SeverityWarning }

func (ruleCOR002) Check(stmts []*pg_query.RawStmt, src string) []diagnostics.Diagnostic {
	var out []diagnostics.Diagnostic
	for _, raw := range stmts {
		u, ok := raw.Stmt.GetNode().(*pg_query.Node_UpdateStmt)
		if !ok {
			continue
		}
		if u.UpdateStmt.WhereClause != nil {
			continue
		}
		line, col := pgast.LocationToLineCol(src, pgast.FirstTokenOffset(src, int(raw.StmtLocation)))
		out = append(out, diagnostics.Diagnostic{
			RuleID:   "COR002",
			Severity: diagnostics.SeverityWarning,
			Message:  fmt.Sprintf("UPDATE %q has no WHERE clause; this modifies every row", relName(u.UpdateStmt.Relation)),
			Line:     line,
			Col:      col,
		})
	}
	return out
}

// COR003 — DELETE without WHERE.
// A DELETE with no WHERE clause removes every row from the table.
// Use TRUNCATE if you intend a full wipe; it is faster and explicit.
type ruleCOR003 struct{}

func (ruleCOR003) ID() string                     { return "COR003" }
func (ruleCOR003) Severity() diagnostics.Severity { return diagnostics.SeverityWarning }

func (ruleCOR003) Check(stmts []*pg_query.RawStmt, src string) []diagnostics.Diagnostic {
	var out []diagnostics.Diagnostic
	for _, raw := range stmts {
		d, ok := raw.Stmt.GetNode().(*pg_query.Node_DeleteStmt)
		if !ok {
			continue
		}
		if d.DeleteStmt.WhereClause != nil {
			continue
		}
		line, col := pgast.LocationToLineCol(src, pgast.FirstTokenOffset(src, int(raw.StmtLocation)))
		out = append(out, diagnostics.Diagnostic{
			RuleID:   "COR003",
			Severity: diagnostics.SeverityWarning,
			Message:  fmt.Sprintf("DELETE FROM %q has no WHERE clause; this removes every row (use TRUNCATE if intentional)", relName(d.DeleteStmt.Relation)),
			Line:     line,
			Col:      col,
		})
	}
	return out
}