// Copyright 2022 The Dawn & Tint Authors
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package time

import (
	"context"
	"flag"
	"fmt"
	"math"
	"sort"
	"time"

	"dawn.googlesource.com/dawn/tools/src/auth"
	"dawn.googlesource.com/dawn/tools/src/cmd/cts/common"
	"dawn.googlesource.com/dawn/tools/src/cts/query"
	"dawn.googlesource.com/dawn/tools/src/cts/result"
	"dawn.googlesource.com/dawn/tools/src/subcmd"
	"go.chromium.org/luci/auth/client/authcli"
)

func init() {
	common.Register(&cmd{})
}

type cmd struct {
	flags struct {
		source    common.ResultSource
		auth      authcli.Flags
		tags      string
		query     string
		aggregate bool
		topN      int
		histogram bool
	}
}

func (cmd) Name() string {
	return "time"
}

func (cmd) Desc() string {
	return "displays timing information for tests"
}

func (c *cmd) RegisterFlags(ctx context.Context, cfg common.Config) ([]string, error) {
	c.flags.source.RegisterFlags(cfg)
	c.flags.auth.Register(flag.CommandLine, auth.DefaultAuthOptions())
	flag.IntVar(&c.flags.topN, "top", 0, "print the top N slowest tests")
	flag.BoolVar(&c.flags.histogram, "histogram", false, "print a histogram of test timings")
	flag.StringVar(&c.flags.query, "query", "", "test query to filter results")
	flag.StringVar(&c.flags.tags, "tags", "", "comma-separated list of tags to filter results")
	flag.BoolVar(&c.flags.aggregate, "aggregate", false, "aggregate times by test")
	return nil, nil
}

func (c *cmd) Run(ctx context.Context, cfg common.Config) error {
	// Validate command line arguments
	auth, err := c.flags.auth.Options()
	if err != nil {
		return fmt.Errorf("failed to obtain authentication options: %w", err)
	}

	// Obtain the resultsByExecutionMode
	resultsByExecutionMode, err := c.flags.source.GetResults(ctx, cfg, auth)
	if err != nil {
		return err
	}

	if len(resultsByExecutionMode) == 0 {
		return fmt.Errorf("no results found")
	}

	// If tags were provided, filter the results to those that contain these tags
	if c.flags.tags != "" {
		for name := range resultsByExecutionMode {
			resultsByExecutionMode[name] = resultsByExecutionMode[name].FilterByTags(result.StringToTags(c.flags.tags))
		}
		if len(resultsByExecutionMode) == 0 {
			return fmt.Errorf("no results after filtering by tags")
		}
	}

	if c.flags.query != "" {
		for name := range resultsByExecutionMode {
			resultsByExecutionMode[name] = resultsByExecutionMode[name].FilterByQuery(query.Parse(c.flags.query))
		}
		if len(resultsByExecutionMode) == 0 {
			return fmt.Errorf("no results after filtering by test query")
		}
	}

	if c.flags.aggregate {
		type Key struct {
			Query  query.Query
			Status result.Status
			Tags   string
		}
		merged := map[Key]result.Result{}
		for name, results := range resultsByExecutionMode {
			for _, r := range results {
				k := Key{
					Query: query.Query{
						Suite: r.Query.Suite,
						Files: r.Query.Files,
						Tests: r.Query.Tests,
						Cases: "*",
					},
					Status: r.Status,
					Tags:   result.TagsToString(r.Tags),
				}
				entry, exists := merged[k]
				if exists {
					entry.Duration += r.Duration
				} else {
					entry = result.Result{
						Query:    k.Query,
						Duration: r.Duration,
						Status:   r.Status,
						Tags:     r.Tags,
					}
				}
				merged[k] = entry
			}

			newResultList := result.List{}
			for _, r := range merged {
				newResultList = append(results, r)
			}
			resultsByExecutionMode[name] = newResultList
		}
	}

	// Sort the results with longest duration first
	for name, results := range resultsByExecutionMode {
		sort.Slice(results, func(i, j int) bool {
			return results[i].Duration > results[j].Duration
		})
		resultsByExecutionMode[name] = results
	}

	didSomething := false

	// Did the user request --top N ?
	if c.flags.topN > 0 {
		didSomething = true
		for name, results := range resultsByExecutionMode {
			topN := results
			if c.flags.topN < len(results) {
				topN = topN[:c.flags.topN]
			}
			for i, r := range topN {
				fmt.Printf("%s %3.1d: %v\n", name, i, r)
			}
		}
	}

	// Did the user request --histogram ?
	if c.flags.histogram {
		for name, results := range resultsByExecutionMode {
			maxTime := results[0].Duration

			const (
				numBins = 25
				pow     = 2.0
			)

			binToDuration := func(i int) time.Duration {
				frac := math.Pow(float64(i)/float64(numBins), pow)
				return time.Duration(float64(maxTime) * frac)
			}
			durationToBin := func(d time.Duration) int {
				frac := math.Pow(float64(d)/float64(maxTime), 1.0/pow)
				idx := int(frac * numBins)
				if idx >= numBins-1 {
					return numBins - 1
				}
				return idx
			}

			didSomething = true
			bins := make([]int, numBins)
			for _, r := range results {
				idx := durationToBin(r.Duration)
				bins[idx] = bins[idx] + 1
			}
			fmt.Printf("%s\n", name)
			for i, bin := range bins {
				fmt.Printf("[%.8v, %.8v]: %v\n", binToDuration(i), binToDuration(i+1), bin)
			}
		}
	}

	// If the user didn't request anything, show a helpful message
	if !didSomething {
		fmt.Fprintln(flag.CommandLine.Output(), "no action flags specified for", c.Name())
		fmt.Fprintln(flag.CommandLine.Output())
		flag.Usage()
		return subcmd.ErrInvalidCLA
	}

	return nil
}