// Copyright (c) 2012 The Gocov Authors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

package main

import (
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"text/tabwriter"

	"github.com/axw/gocov"
)

type report struct {
	packages []*gocov.Package
}

type reportFunction struct {
	*gocov.Function
	statementsReached int
}

type reportFunctionList []reportFunction

func (l reportFunctionList) Len() int {
	return len(l)
}

// TODO make sort method configurable?
func (l reportFunctionList) Less(i, j int) bool {
	var left, right float64
	if len(l[i].Statements) > 0 {
		left = float64(l[i].statementsReached) / float64(len(l[i].Statements))
	}
	if len(l[j].Statements) > 0 {
		right = float64(l[j].statementsReached) / float64(len(l[j].Statements))
	}
	if left < right {
		return true
	}
	return left == right && len(l[i].Statements) < len(l[j].Statements)
}

func (l reportFunctionList) Swap(i, j int) {
	l[i], l[j] = l[j], l[i]
}

type reverse struct {
	sort.Interface
}

func (r reverse) Less(i, j int) bool {
	return r.Interface.Less(j, i)
}

// NewReport creates a new report.
func newReport() (r *report) {
	r = &report{}
	return
}

// AddPackage adds a package's coverage information to the report.
func (r *report) addPackage(p *gocov.Package) {
	i := sort.Search(len(r.packages), func(i int) bool {
		return r.packages[i].Name >= p.Name
	})
	if i < len(r.packages) && r.packages[i].Name == p.Name {
		r.packages[i].Accumulate(p)
	} else {
		head := r.packages[:i]
		tail := append([]*gocov.Package{p}, r.packages[i:]...)
		r.packages = append(head, tail...)
	}
}

// Clear clears the coverage information from the report.
func (r *report) clear() {
	r.packages = nil
}

// functionReports returns the packages functions as an array of
// reportFunction objects with the statements reached calculated
func functionReports(pkg *gocov.Package) reportFunctionList {
	functions := make(reportFunctionList, len(pkg.Functions))
	for i, fn := range pkg.Functions {
		reached := 0
		for _, stmt := range fn.Statements {
			if stmt.Reached > 0 {
				reached++
			}
		}
		functions[i] = reportFunction{fn, reached}
	}

	return functions

}

// printTotalCoverage outputs the combined coverage for each
// package
func (r *report) printTotalCoverage(w io.Writer) {
	var totalStatements, totalReached int

	for _, pkg := range r.packages {
		functions := functionReports(pkg)
		sort.Sort(reverse{functions})

		for _, fn := range functions {
			reached := fn.statementsReached
			totalStatements += len(fn.Statements)
			totalReached += reached
		}
	}

	coveragePercentage := float64(totalReached) / float64(totalStatements) * 100
	fmt.Fprintf(w, "Total Coverage: %.2f%% (%d/%d)", coveragePercentage, totalReached, totalStatements)
	fmt.Fprintln(w)
}

// PrintReport prints a coverage report to the given writer.
func printReport(w io.Writer, r *report) {
	w = tabwriter.NewWriter(w, 0, 8, 0, '\t', 0)
	//fmt.Fprintln(w, "Package\tFunction\tStatements\t")
	//fmt.Fprintln(w, "-------\t--------\t---------\t")
	for _, pkg := range r.packages {
		printPackage(w, pkg)
		fmt.Fprintln(w)
	}
	r.printTotalCoverage(w)
}

func printPackage(w io.Writer, pkg *gocov.Package) {
	functions := functionReports(pkg)
	sort.Sort(reverse{functions})

	var longestFunctionName int
	var totalStatements, totalReached int
	for _, fn := range functions {
		reached := fn.statementsReached
		totalStatements += len(fn.Statements)
		totalReached += reached
		var stmtPercent float64 = 0
		if len(fn.Statements) > 0 {
			stmtPercent = float64(reached) / float64(len(fn.Statements)) * 100
		}
		if len(fn.Name) > longestFunctionName {
			longestFunctionName = len(fn.Name)
		}
		fmt.Fprintf(w, "%s/%s\t %s\t %.2f%% (%d/%d)\n",
			pkg.Name, filepath.Base(fn.File), fn.Name, stmtPercent,
			reached, len(fn.Statements))
	}

	var funcPercent float64
	if totalStatements > 0 {
		funcPercent = float64(totalReached) / float64(totalStatements) * 100
	}
	summaryLine := strings.Repeat("-", longestFunctionName)
	fmt.Fprintf(w, "%s\t %s\t %.2f%% (%d/%d)\n",
		pkg.Name, summaryLine, funcPercent,
		totalReached, totalStatements)
}

func reportCoverage() (rc int) {
	files := make([]*os.File, 0, 1)
	if flag.NArg() > 1 {
		for _, name := range flag.Args()[1:] {
			file, err := os.Open(name)
			if err != nil {
				fmt.Fprintf(os.Stderr, "failed to open file (%s): %s\n", name, err)
			} else {
				files = append(files, file)
			}
		}
	} else {
		files = append(files, os.Stdin)
	}
	report := newReport()
	for _, file := range files {
		data, err := ioutil.ReadAll(file)
		if err != nil {
			fmt.Fprintf(os.Stderr, "failed to read coverage file: %s\n", err)
			return 1
		}
		packages, err := unmarshalJson(data)
		if err != nil {
			fmt.Fprintf(
				os.Stderr, "failed to unmarshal coverage data: %s\n", err)
			return 1
		}
		for _, pkg := range packages {
			report.addPackage(pkg)
		}
		if file != os.Stdin {
			file.Close()
		}
	}
	fmt.Println()
	printReport(os.Stdout, report)
	return 0
}