package diagnostics

import (
	"encoding/json"
	"fmt"
	"log/slog"
	"os"
	"strings"
	"time"

	"github.com/github/codeql-go/extractor/util"
)

type sourceStruct struct {
	Id            string `json:"id"`
	Name          string `json:"name"`
	ExtractorName string `json:"extractorName"`
}

type diagnosticSeverity string

const (
	severityError   diagnosticSeverity = "error"
	severityWarning diagnosticSeverity = "warning"
	severityNote    diagnosticSeverity = "note"
)

type visibilityStruct struct {
	StatusPage      bool `json:"statusPage"`      // True if the message should be displayed on the status page (defaults to false)
	CliSummaryTable bool `json:"cliSummaryTable"` // True if the message should be counted in the diagnostics summary table printed by `codeql database analyze` (defaults to false)
	Telemetry       bool `json:"telemetry"`       // True if the message should be sent to telemetry (defaults to false)
}

var fullVisibility *visibilityStruct = &visibilityStruct{true, true, true}
var telemetryOnly *visibilityStruct = &visibilityStruct{false, false, true}

type locationStruct struct {
	File        string `json:"file,omitempty"`
	StartLine   int    `json:"startLine,omitempty"`
	StartColumn int    `json:"startColumn,omitempty"`
	EndLine     int    `json:"endLine,omitempty"`
	EndColumn   int    `json:"endColumn,omitempty"`
}

var noLocation *locationStruct = nil

type diagnostic struct {
	Timestamp       string            `json:"timestamp"`
	Source          sourceStruct      `json:"source"`
	MarkdownMessage string            `json:"markdownMessage"`
	Severity        string            `json:"severity"`
	Visibility      *visibilityStruct `json:"visibility,omitempty"` // Use a pointer so that it is omitted if nil
	Location        *locationStruct   `json:"location,omitempty"`   // Use a pointer so that it is omitted if nil
}

var diagnosticsEmitted, diagnosticsLimit uint = 0, 100
var noDiagnosticDirPrinted bool = false

type DiagnosticsWriter interface {
	WriteDiagnostic(d diagnostic)
}

type FileDiagnosticsWriter struct {
	diagnosticDir string
}

func (writer *FileDiagnosticsWriter) WriteDiagnostic(d diagnostic) {
	if writer == nil {
		return
	}

	content, err := json.Marshal(d)
	if err != nil {
		slog.Error("Failed to encode diagnostic as JSON", slog.Any("err", err))
		return
	}

	targetFile, err := os.CreateTemp(writer.diagnosticDir, "go-extractor.*.json")
	if err != nil {
		slog.Error("Failed to create diagnostic file", slog.Any("err", err))
		return
	}
	defer func() {
		if err := targetFile.Close(); err != nil {
			slog.Error("Failed to close diagnostic file", slog.Any("err", err))
		}
	}()

	_, err = targetFile.Write(content)
	if err != nil {
		slog.Error("Failed to write to diagnostic file", slog.Any("err", err))
	}
}

var DefaultWriter *FileDiagnosticsWriter = nil

func NewFileDiagnosticsWriter() *FileDiagnosticsWriter {
	diagnosticDir := os.Getenv("CODEQL_EXTRACTOR_GO_DIAGNOSTIC_DIR")
	if diagnosticDir == "" {
		if !noDiagnosticDirPrinted {
			slog.Warn("No diagnostic directory set, so not emitting diagnostics")
			noDiagnosticDirPrinted = true
		}
		return nil
	}

	return &FileDiagnosticsWriter{diagnosticDir}
}

func init() {
	DefaultWriter = NewFileDiagnosticsWriter()
}

// Emits a diagnostic using the specified `DiagnosticsWriter`.
func emitDiagnosticTo(writer DiagnosticsWriter, sourceid, sourcename, markdownMessage string, severity diagnosticSeverity, visibility *visibilityStruct, location *locationStruct) {
	if diagnosticsEmitted < diagnosticsLimit {
		diagnosticsEmitted += 1

		timestamp := time.Now().UTC().Format("2006-01-02T15:04:05.000") + "Z"

		var d diagnostic

		if diagnosticsEmitted < diagnosticsLimit {
			d = diagnostic{
				timestamp,
				sourceStruct{sourceid, sourcename, "go"},
				markdownMessage,
				string(severity),
				visibility,
				location,
			}
		} else {
			d = diagnostic{
				timestamp,
				sourceStruct{"go/autobuilder/diagnostic-limit-reached", "Diagnostics limit exceeded", "go"},
				fmt.Sprintf("CodeQL has produced more than the maximum number of diagnostics. Only the first %d have been reported.", diagnosticsLimit),
				string(severityWarning),
				fullVisibility,
				noLocation,
			}
		}

		writer.WriteDiagnostic(d)
	}
}

// Emits a diagnostic using the default `DiagnosticsWriter`.
func emitDiagnostic(sourceid, sourcename, markdownMessage string, severity diagnosticSeverity, visibility *visibilityStruct, location *locationStruct) {
	emitDiagnosticTo(DefaultWriter, sourceid, sourcename, markdownMessage, severity, visibility, location)
}

func EmitPackageDifferentOSArchitecture(pkgPath string) {
	emitDiagnostic(
		"go/autobuilder/package-different-os-architecture",
		"An imported package is intended for a different OS or architecture",
		"`"+pkgPath+"` could not be imported. Make sure the `GOOS` and `GOARCH` [environment variables are correctly set](https://docs.github.com/en/actions/learn-github-actions/variables#defining-environment-variables-for-a-single-workflow). Alternatively, [change your OS and architecture](https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#using-a-github-hosted-runner).",
		severityWarning,
		fullVisibility,
		noLocation,
	)
}

func plural(n int, singular, plural string) string {
	if n == 1 {
		return singular
	} else {
		return plural
	}
}

const maxNumPkgPaths = 5

func EmitCannotFindPackages(writer DiagnosticsWriter, pkgPaths []string) {
	numPkgPaths := len(pkgPaths)

	numPrinted := numPkgPaths
	truncated := false
	if numPrinted > maxNumPkgPaths {
		numPrinted = maxNumPkgPaths
		truncated = true
	}

	secondLine := "`" + strings.Join(pkgPaths[0:numPrinted], "`, `") + "`"
	if truncated {
		secondLine += fmt.Sprintf(" and %d more", numPkgPaths-maxNumPkgPaths)
	}

	message := fmt.Sprintf(
		"%d package%s could not be found:\n\n%s.\n\n"+
			"CodeQL is able to analyze your code without those packages, but definitions from them may not be recognized and "+
			"source files that use them may only be partially analyzed.\n\n"+
			"To ensure that you have comprehensive alert coverage, check that the paths are correct and make sure any private packages can be accessed by CodeQL. ",
		numPkgPaths,
		plural(len(pkgPaths), "", "s"),
		secondLine,
	)

	// Depending on the environment we are running in, provide a different message for how to configure access to private registries.
	if util.IsDynamicActionsWorkflow() {
		// For GitHub-managed (dynamic) workflows, we offer built-in support for private registries that customers can set up.
		message = message +
			"Organizations [can grant access to private registries for GitHub security products](https://docs.github.com/en/code-security/how-tos/secure-at-scale/configure-organization-security/manage-usage-and-access/giving-org-access-private-registries). "
	} else {
		if util.IsActionsWorkflow() {
			// For custom workflows, users can add a workflow step to set up credentials or environment variables.
			message = message +
				"To set up access to a private registry, add a step to your workflow which sets up the necessary credentials and environment variables. "
		} else {
			// Otherwise, we are running locally or in some other CI system.
			message = message +
				"To set up access to private registries, ensure that the necessary credentials and environment variables are set up for `go` to use. "
		}

		// This should be less likely since we improved Go project discovery. We only include it in the message if we are not running in a
		// GitHub-managed workflow, since users would not be able to act on this there.
		message = message +
			"If any of the packages are already present in the repository, but were not found, then you may need a [custom build command](https://docs.github.com/en/code-security/how-tos/scan-code-for-vulnerabilities/manage-your-configuration/codeql-code-scanning-for-compiled-languages)."
	}

	emitDiagnosticTo(
		writer,
		"go/autobuilder/package-not-found",
		"Some packages could not be found",
		message,
		severityWarning,
		fullVisibility,
		noLocation,
	)
}

func EmitNewerGoVersionNeeded(installedVersion string, requiredVersion string) {
	emitDiagnostic(
		"go/autobuilder/newer-go-version-needed",
		"Newer Go version needed",
		"Version `"+installedVersion+"` of Go is installed, but this is lower than `"+requiredVersion+"` required by your project's `go.mod`. [Install a newer version of Go before analyzing your project](https://github.com/actions/setup-go#basic).",
		severityError,
		fullVisibility,
		noLocation,
	)
}

func EmitGoFilesFoundButNotProcessed() {
	emitDiagnostic(
		"go/autobuilder/go-files-found-but-not-processed",
		"Go files were found but not processed",
		"[Specify a custom build command](https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/configuring-the-codeql-workflow-for-compiled-languages) that includes one or more `go build` commands to build the `.go` files to be analyzed.",
		severityError,
		fullVisibility,
		noLocation,
	)
}

func EmitRelativeImportPaths() {
	emitDiagnostic(
		"go/autobuilder/relative-import-paths",
		"Some imports use unsupported relative package paths",
		"You should replace relative package paths (that contain `.` or `..`) with absolute paths. Alternatively you can [use a Go module](https://go.dev/blog/using-go-modules).",
		severityError,
		fullVisibility,
		noLocation,
	)
}

// The following diagnostics are telemetry-only.

func EmitBazelBuildFilesFound(bazelPaths []string) {
	emitDiagnostic(
		"go/autobuilder/bazel-build-file-found",
		"Bazel BUILD files were found",
		fmt.Sprintf(
			"%d bazel BUILD %s found:\n\n`%s`",
			len(bazelPaths),
			plural(len(bazelPaths), "file was", "files were"),
			strings.Join(bazelPaths, "`, `")),
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGopkgTomlFound() {
	emitDiagnostic(
		"go/autobuilder/gopkg-toml-found",
		"A dep `Gopkg.toml` file was found",
		"A dep `Gopkg.toml` file was found",
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGlideYamlFound() {
	emitDiagnostic(
		"go/autobuilder/glide-yaml-found",
		"A Glide `glide.yaml` file was found",
		"A Glide `glide.yaml` file was found",
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoWorkFound(goWorkPaths []string) {
	emitDiagnostic(
		"go/autobuilder/go-work-found",
		"`go.work` file found",
		fmt.Sprintf(
			"%d `go.work` %s found:\n\n`%s`",
			len(goWorkPaths),
			plural(len(goWorkPaths), "file was", "files were"),
			strings.Join(goWorkPaths, "`, `")),
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoFilesOutsideGoModules(goModPaths []string) {
	emitDiagnostic(
		"go/autobuilder/go-files-outside-go-modules",
		"Go files were found outside Go modules",
		"Go files were found outside of the Go modules corresponding to these `go.mod` files.\n\n`"+strings.Join(goModPaths, "`, `")+"`",
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitMultipleGoModFoundNested(goModPaths []string) {
	emitDiagnostic(
		"go/autobuilder/multiple-go-mod-found-nested",
		"Multiple `go.mod` files were found, all nested under one root `go.mod` file",
		fmt.Sprintf(
			"%d `go.mod` files were found:\n\n`%s`",
			len(goModPaths),
			strings.Join(goModPaths, "`, `")),
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitMultipleGoModFoundNotNested(goModPaths []string) {
	emitDiagnostic(
		"go/autobuilder/multiple-go-mod-found-not-nested",
		"Multiple `go.mod` files found, not all nested under one root `go.mod` file",
		fmt.Sprintf(
			"%d `go.mod` files were found:\n\n`%s`",
			len(goModPaths),
			strings.Join(goModPaths, "`, `")),
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitSingleRootGoModFound(goModPath string) {
	emitDiagnostic(
		"go/autobuilder/single-root-go-mod-found",
		"A single `go.mod` file was found in the root",
		"A single `go.mod` file was found.\n\n`"+goModPath+"`",
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitSingleNonRootGoModFound(goModPath string) {
	emitDiagnostic(
		"go/autobuilder/single-non-root-go-mod-found",
		"A single, non-root `go.mod` file was found",
		"A single, non-root `go.mod` file was found.\n\n`"+goModPath+"`",
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

// The following diagnostics are related to identifying the build environment.

func EmitNoGoModAndNoGoEnv(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-no-go-mod-no-go-env",
		"No `go.mod` file found and no Go version in environment",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitNoGoModAndGoEnvUnsupported(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-no-go-mod-go-env-unsupported",
		"No `go.mod` file found and Go version in environment is unsupported",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitNoGoModAndGoEnvSupported(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-no-go-mod-go-env-supported",
		"No `go.mod` file found and Go version in environment is supported",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooHighAndNoGoEnv(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-high-no-go-env",
		"Go version in `go.mod` file above supported range and no Go version in environment",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooHighAndEnvVersionTooHigh(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-high-go-env-too-high",
		"Go version in `go.mod` file above supported range and Go version in environment above supported range",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooHighAndEnvVersionTooLow(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-high-go-env-too-low",
		"Go version in `go.mod` file above supported range and Go version in environment below supported range",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooHighAndEnvVersionBelowMax(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-high-go-env-below-max",
		"Go version in `go.mod` file above supported range and Go version in environment is supported and below the maximum supported version",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooHighAndEnvVersionMax(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-high-go-env-max",
		"Go version in `go.mod` file above supported range and Go version in environment is the maximum supported version",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooLowAndNoGoEnv(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-low-no-go-env",
		"Go version in `go.mod` file below supported range and no Go version in environment",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooLowAndEnvVersionUnsupported(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-low-go-env-unsupported",
		"Go version in `go.mod` file below supported range and Go version in environment unsupported",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionTooLowAndEnvVersionSupported(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-too-low-go-env-supported",
		"Go version in `go.mod` file below supported range and Go version in environment supported",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionSupportedAndNoGoEnv(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-supported-no-go-env",
		"Go version in `go.mod` file in supported range and no Go version in environment",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionSupportedAndGoEnvUnsupported(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-supported-go-env-unsupported",
		"Go version in `go.mod` file in supported range and Go version in environment unsupported",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionSupportedHigherGoEnv(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-supported-higher-than-go-env",
		"The Go version in `go.mod` file is supported and higher than the Go version in environment",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitGoModVersionSupportedLowerEqualGoEnv(msg string) {
	emitDiagnostic(
		"go/autobuilder/env-go-mod-version-supported-lower-than-or-equal-to-go-env",
		"The Go version in `go.mod` file is supported and lower than or equal to the Go version in environment",
		msg,
		severityNote,
		telemetryOnly,
		noLocation,
	)
}

func EmitNewerSystemGoRequired(requiredVersion string) {
	emitDiagnostic(
		"go/autobuilder/newer-system-go-version-required",
		"The Go version installed on the system is too old to support this project",
		"At least Go version `"+requiredVersion+"` is required to build this project, but the version installed on the system is older. [Install a newer version](https://github.com/actions/setup-go#basic).",
		severityError,
		fullVisibility,
		noLocation,
	)
}

func EmitExtractionFailedForProjects(path []string) {
	emitDiagnostic(
		"go/autobuilder/extraction-failed-for-project",
		"Unable to extract some Go projects",
		fmt.Sprintf(
			"The following %d Go project%s could not be extracted successfully:\n\n`%s`\n",
			len(path),
			plural(len(path), "", "s"),
			strings.Join(path, "`, `")),
		severityWarning,
		fullVisibility,
		noLocation,
	)
}

func EmitPrivateRegistryUsed(writer DiagnosticsWriter, configs []string) {
	n := len(configs)
	lines := make([]string, n)

	for i := range configs {
		lines[i] = fmt.Sprintf("* %s", configs[i])
	}

	emitDiagnosticTo(
		writer,
		"go/autobuilder/analysis-using-private-registries",
		"Go extraction used private package registries",
		fmt.Sprintf(
			"Go was extracted using the following private package registr%s:\n\n%s\n",
			plural(n, "y", "ies"),
			strings.Join(lines, "\n")),
		severityNote,
		fullVisibility,
		noLocation,
	)
}