package gotest

import (
	"time"

	"github.com/jstemmer/go-junit-report/v2/gtr"
)

// reportBuilder helps build a test Report from a collection of events.
//
// The reportBuilder keeps track of the active context whenever a test,
// benchmark or build error is created. This is necessary because the test
// parser do not contain any state themselves and simply just emit an event for
// every line that is read. By tracking the active context, any output that is
// appended to the reportBuilder gets attributed to the correct test, benchmark
// or build error.
type reportBuilder struct {
	packages    []gtr.Package
	tests       map[int]gtr.Test
	benchmarks  map[int]gtr.Benchmark
	buildErrors map[int]gtr.Error
	runErrors   map[int]gtr.Error

	// state
	nextID   int      // next free unused id
	lastID   int      // most recently created id
	output   []string // output that does not belong to any test
	coverage float64  // coverage percentage

	// options
	packageName   string
	timestampFunc func() time.Time
}

// newReportBuilder creates a new reportBuilder.
func newReportBuilder() *reportBuilder {
	return &reportBuilder{
		tests:         make(map[int]gtr.Test),
		benchmarks:    make(map[int]gtr.Benchmark),
		buildErrors:   make(map[int]gtr.Error),
		runErrors:     make(map[int]gtr.Error),
		nextID:        1,
		timestampFunc: time.Now,
	}
}

// newID returns a new unique id and sets the active context this id.
func (b *reportBuilder) newID() int {
	id := b.nextID
	b.lastID = id
	b.nextID += 1
	return id
}

// flush creates a new package in this report containing any tests or
// benchmarks we've collected so far. This is necessary when a test or
// benchmark did not end with a summary.
func (b *reportBuilder) flush() {
	if len(b.tests) > 0 || len(b.benchmarks) > 0 {
		b.CreatePackage(b.packageName, "", 0, "")
	}
}

// Build returns the new Report containing all the tests, benchmarks and output
// created so far.
func (b *reportBuilder) Build() gtr.Report {
	b.flush()
	return gtr.Report{Packages: b.packages}
}

// CreateTest adds a test with the given name to the report, and marks it as
// active.
func (b *reportBuilder) CreateTest(name string) {
	b.tests[b.newID()] = gtr.Test{Name: name}
}

// PauseTest marks the active context as no longer active. Any results or
// output added to the report after calling PauseTest will no longer be assumed
// to belong to this test.
func (b *reportBuilder) PauseTest(name string) {
	b.lastID = 0
}

// ContinueTest finds the test with the given name and marks it as active. If
// more than one test exist with this name, the most recently created test will
// be used.
func (b *reportBuilder) ContinueTest(name string) {
	b.lastID = b.findTest(name)
}

// EndTest finds the test with the given name, sets the result, duration and
// level. If more than one test exists with this name, the most recently
// created test will be used. If no test exists with this name, a new test is
// created.
func (b *reportBuilder) EndTest(name, result string, duration time.Duration, level int) {
	b.lastID = b.findTest(name)
	if b.lastID < 0 {
		// test did not exist, create one
		// TODO: Likely reason is that the user ran go test without the -v
		// flag, should we report this somewhere?
		b.CreateTest(name)
	}

	t := b.tests[b.lastID]
	t.Result = parseResult(result)
	t.Duration = duration
	t.Level = level
	b.tests[b.lastID] = t
	b.lastID = 0
}

// End marks the active context as no longer active.
func (b *reportBuilder) End() {
	b.lastID = 0
}

// CreateBenchmark adds a benchmark with the given name to the report, and
// marks it as active. If more than one benchmark exists with this name, the
// most recently created benchmark will be updated. If no benchmark exists with
// this name, a new benchmark is created.
func (b *reportBuilder) CreateBenchmark(name string) {
	b.benchmarks[b.newID()] = gtr.Benchmark{
		Name: name,
	}
}

// BenchmarkResult updates an existing or adds a new benchmark with the given
// results and marks it as active. If an existing benchmark with this name
// exists but without result, then that one is updated. Otherwise a new one is
// added to the report.
func (b *reportBuilder) BenchmarkResult(name string, iterations int64, nsPerOp, mbPerSec float64, bytesPerOp, allocsPerOp int64) {
	b.lastID = b.findBenchmark(name)
	if b.lastID < 0 || b.benchmarks[b.lastID].Result != gtr.Unknown {
		b.CreateBenchmark(name)
	}

	b.benchmarks[b.lastID] = gtr.Benchmark{
		Name:        name,
		Result:      gtr.Pass,
		Iterations:  iterations,
		NsPerOp:     nsPerOp,
		MBPerSec:    mbPerSec,
		BytesPerOp:  bytesPerOp,
		AllocsPerOp: allocsPerOp,
	}
}

// EndBenchmark finds the benchmark with the given name and sets the result. If
// more than one benchmark exists with this name, the most recently created
// benchmark will be used. If no benchmark exists with this name, a new
// benchmark is created.
func (b *reportBuilder) EndBenchmark(name, result string) {
	b.lastID = b.findBenchmark(name)
	if b.lastID < 0 {
		b.CreateBenchmark(name)
	}

	bm := b.benchmarks[b.lastID]
	bm.Result = parseResult(result)
	b.benchmarks[b.lastID] = bm
	b.lastID = 0
}

// CreateBuildError creates a new build error and marks it as active.
func (b *reportBuilder) CreateBuildError(packageName string) {
	b.buildErrors[b.newID()] = gtr.Error{Name: packageName}
}

// CreatePackage adds a new package with the given name to the Report. This
// package contains all the build errors, output, tests and benchmarks created
// so far. Afterwards all state is reset.
func (b *reportBuilder) CreatePackage(name, result string, duration time.Duration, data string) {
	pkg := gtr.Package{
		Name:     name,
		Duration: duration,
	}

	if b.timestampFunc != nil {
		pkg.Timestamp = b.timestampFunc()
	}

	// Build errors are treated somewhat differently. Rather than having a
	// single package with all build errors collected so far, we only care
	// about the build errors for this particular package.
	for id, buildErr := range b.buildErrors {
		if buildErr.Name == name {
			if len(b.tests) > 0 || len(b.benchmarks) > 0 {
				panic("unexpected tests and/or benchmarks found in build error package")
			}
			buildErr.Duration = duration
			buildErr.Cause = data
			pkg.BuildError = buildErr
			b.packages = append(b.packages, pkg)

			delete(b.buildErrors, id)
			// TODO: reset state
			// TODO: buildErrors shouldn't reset/use nextID/lastID, they're more like a global cache
			return
		}
	}

	// If we've collected output, but there were no tests or benchmarks then
	// either there were no tests, or there was some other non-build error.
	if len(b.output) > 0 && len(b.tests) == 0 && len(b.benchmarks) == 0 {
		if parseResult(result) == gtr.Fail {
			pkg.RunError = gtr.Error{
				Name:   name,
				Output: b.output,
			}
		}
		b.packages = append(b.packages, pkg)

		// TODO: reset state
		b.output = nil
		return
	}

	// If the summary result says we failed, but there were no failing tests
	// then something else must have failed.
	if parseResult(result) == gtr.Fail && (len(b.tests) > 0 || len(b.benchmarks) > 0) && !b.containsFailingTest() {
		pkg.RunError = gtr.Error{
			Name:   name,
			Output: b.output,
		}
		b.output = nil
	}

	// Collect tests and benchmarks for this package, maintaining insertion order.
	var tests []gtr.Test
	var benchmarks []gtr.Benchmark
	for id := 1; id < b.nextID; id++ {
		if t, ok := b.tests[id]; ok {
			tests = append(tests, t)
		}
		if bm, ok := b.benchmarks[id]; ok {
			benchmarks = append(benchmarks, bm)
		}
	}

	pkg.Coverage = b.coverage
	pkg.Output = b.output
	pkg.Tests = tests
	pkg.Benchmarks = benchmarks
	b.packages = append(b.packages, pkg)

	// reset state
	b.nextID = 1
	b.lastID = 0
	b.output = nil
	b.coverage = 0
	b.tests = make(map[int]gtr.Test)
	b.benchmarks = make(map[int]gtr.Benchmark)
}

// Coverage sets the code coverage percentage.
func (b *reportBuilder) Coverage(pct float64, packages []string) {
	b.coverage = pct
}

// AppendOutput appends the given line to the currently active context. If no
// active context exists, the output is assumed to belong to the package.
func (b *reportBuilder) AppendOutput(line string) {
	if b.lastID <= 0 {
		b.output = append(b.output, line)
		return
	}

	if t, ok := b.tests[b.lastID]; ok {
		t.Output = append(t.Output, line)
		b.tests[b.lastID] = t
	} else if bm, ok := b.benchmarks[b.lastID]; ok {
		bm.Output = append(bm.Output, line)
		b.benchmarks[b.lastID] = bm
	} else if be, ok := b.buildErrors[b.lastID]; ok {
		be.Output = append(be.Output, line)
		b.buildErrors[b.lastID] = be
	} else {
		b.output = append(b.output, line)
	}
}

// findTest returns the id of the most recently created test with the given
// name, or -1 if no such test exists.
func (b *reportBuilder) findTest(name string) int {
	// check if this test was lastID
	if t, ok := b.tests[b.lastID]; ok && t.Name == name {
		return b.lastID
	}
	for id := len(b.tests); id >= 0; id-- {
		if b.tests[id].Name == name {
			return id
		}
	}
	return -1
}

// findBenchmark returns the id of the most recently created benchmark with the
// given name, or -1 if no such benchmark exists.
func (b *reportBuilder) findBenchmark(name string) int {
	// check if this benchmark was lastID
	if bm, ok := b.benchmarks[b.lastID]; ok && bm.Name == name {
		return b.lastID
	}
	for id := len(b.benchmarks); id >= 0; id-- {
		if b.benchmarks[id].Name == name {
			return id
		}
	}
	return -1
}

// containsFailingTest return true if the current list of tests contains at
// least one failing test or an unknown result.
func (b *reportBuilder) containsFailingTest() bool {
	for _, test := range b.tests {
		if test.Result == gtr.Fail || test.Result == gtr.Unknown {
			return true
		}
	}
	return false
}

// parseResult returns a Result for the given string r.
func parseResult(r string) gtr.Result {
	switch r {
	case "PASS":
		return gtr.Pass
	case "FAIL":
		return gtr.Fail
	case "SKIP":
		return gtr.Skip
	case "BENCH":
		return gtr.Pass
	default:
		return gtr.Unknown
	}
}