/*
Copyright 2020 Google LLC

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// General Bazel-related warnings

package warn

import (
	"fmt"
	"strings"

	"github.com/bazelbuild/buildtools/build"
)

var functionsWithPositionalArguments = map[string]bool{
	"distribs":            true,
	"exports_files":       true,
	"licenses":            true,
	"print":               true,
	"register_toolchains": true,
	"vardef":              true,
}

func constantGlobWarning(f *build.File) []*LinterFinding {
	switch f.Type {
	case build.TypeBuild, build.TypeWorkspace, build.TypeBzl:
	default:
		// Not applicable
		return nil
	}

	findings := []*LinterFinding{}
	build.Walk(f, func(expr build.Expr, stack []build.Expr) {
		call, ok := expr.(*build.CallExpr)
		if !ok || len(call.List) == 0 {
			return
		}
		ident, ok := (call.X).(*build.Ident)
		if !ok || ident.Name != "glob" {
			return
		}
		patterns, ok := call.List[0].(*build.ListExpr)
		if !ok {
			return
		}
		for _, expr := range patterns.List {
			str, ok := expr.(*build.StringExpr)
			if !ok {
				continue
			}
			if !strings.Contains(str.Value, "*") {
				message := fmt.Sprintf(
					`Glob pattern %q has no wildcard ('*'). Constant patterns can be error-prone, move the file outside the glob.`, str.Value)
				findings = append(findings, makeLinterFinding(expr, message))
				return // at most one warning per glob
			}
		}
	})
	return findings
}

func nativeInBuildFilesWarning(f *build.File) []*LinterFinding {
	if f.Type != build.TypeBuild {
		return nil
	}

	findings := []*LinterFinding{}
	build.WalkPointers(f, func(expr *build.Expr, stack []build.Expr) {
		// Search for `native.xxx` nodes
		dot, ok := (*expr).(*build.DotExpr)
		if !ok {
			return
		}
		ident, ok := dot.X.(*build.Ident)
		if !ok || ident.Name != "native" {
			return
		}

		findings = append(findings,
			makeLinterFinding(ident,
				`The "native" module shouldn't be used in BUILD files, its members are available as global symbols.`,
				LinterReplacement{expr, &build.Ident{Name: dot.Name}}))
	})
	return findings
}

func nativePackageWarning(f *build.File) []*LinterFinding {
	if f.Type != build.TypeBzl {
		return nil
	}

	findings := []*LinterFinding{}
	build.Walk(f, func(expr build.Expr, stack []build.Expr) {
		// Search for `native.package()` nodes
		call, ok := expr.(*build.CallExpr)
		if !ok {
			return
		}
		dot, ok := call.X.(*build.DotExpr)
		if !ok || dot.Name != "package" {
			return
		}
		ident, ok := dot.X.(*build.Ident)
		if !ok || ident.Name != "native" {
			return
		}

		findings = append(findings,
			makeLinterFinding(call, `"native.package()" shouldn't be used in .bzl files.`))
	})
	return findings
}

func duplicatedNameWarning(f *build.File) []*LinterFinding {
	if f.Type != build.TypeBuild && f.Type != build.TypeWorkspace {
		// Not applicable to .bzl files.
		return nil
	}

	findings := []*LinterFinding{}
	names := make(map[string]int) // map from name to line number
	msg := `A rule with name %q was already found on line %d. ` +
		`Even if it's valid for Blaze, this may confuse other tools. ` +
		`Please rename it and use different names.`

	for _, rule := range f.Rules("") {
		name := rule.ExplicitName()
		if name == "" {
			continue
		}
		start, _ := rule.Call.Span()
		if line, ok := names[name]; ok {
			finding := makeLinterFinding(rule.Call, fmt.Sprintf(msg, name, line))
			if nameNode := rule.Attr("name"); nameNode != nil {
				finding.Start, finding.End = nameNode.Span()
				start = finding.Start
			}
			findings = append(findings, finding)
		} else {
			names[name] = start.Line
		}
	}
	return findings
}

func positionalArgumentsWarning(call *build.CallExpr, pkg string) *LinterFinding {
	if id, ok := call.X.(*build.Ident); !ok || functionsWithPositionalArguments[id.Name] {
		return nil
	}
	for _, arg := range call.List {
		if _, ok := arg.(*build.AssignExpr); ok || arg == nil {
			continue
		}
		return makeLinterFinding(arg, "All calls to rules or macros should pass arguments by keyword (arg_name=value) syntax.")
	}
	return nil
}

func argsKwargsInBuildFilesWarning(f *build.File) []*LinterFinding {
	if f.Type != build.TypeBuild {
		return nil
	}

	findings := []*LinterFinding{}
	build.Walk(f, func(expr build.Expr, stack []build.Expr) {
		// Search for function call nodes
		call, ok := expr.(*build.CallExpr)
		if !ok {
			return
		}
		for _, param := range call.List {
			unary, ok := param.(*build.UnaryExpr)
			if !ok {
				continue
			}
			switch unary.Op {
			case "*":
				findings = append(findings,
					makeLinterFinding(param, `*args are not allowed in BUILD files.`))
			case "**":
				findings = append(findings,
					makeLinterFinding(param, `**kwargs are not allowed in BUILD files.`))
			}
		}
	})
	return findings
}

func printWarning(f *build.File) []*LinterFinding {
	if f.Type == build.TypeDefault {
		// Only applicable to Bazel files
		return nil
	}

	findings := []*LinterFinding{}
	build.Walk(f, func(expr build.Expr, stack []build.Expr) {
		call, ok := expr.(*build.CallExpr)
		if !ok {
			return
		}
		ident, ok := (call.X).(*build.Ident)
		if !ok || ident.Name != "print" {
			return
		}
		findings = append(findings,
			makeLinterFinding(expr, `"print()" is a debug function and shouldn't be submitted.`))
	})
	return findings
}