// Copyright 2014 Google Inc. All Rights Reserved.
//
// 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
//
//     http://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.

// Package driver provides an external entry point to the pprof driver.
package driver

import (
	"io"
	"regexp"
	"time"

	internaldriver "github.com/google/pprof/internal/driver"
	"github.com/google/pprof/internal/plugin"
	"github.com/google/pprof/profile"
)

// PProf acquires a profile, and symbolizes it using a profile
// manager. Then it generates a report formatted according to the
// options selected through the flags package.
func PProf(o *Options) error {
	return internaldriver.PProf(o.internalOptions())
}

func (o *Options) internalOptions() *plugin.Options {
	var obj plugin.ObjTool
	if o.Obj != nil {
		obj = &internalObjTool{o.Obj}
	}
	var sym plugin.Symbolizer
	if o.Sym != nil {
		sym = &internalSymbolizer{o.Sym}
	}
	var httpServer func(args *plugin.HTTPServerArgs) error
	if o.HTTPServer != nil {
		httpServer = func(args *plugin.HTTPServerArgs) error {
			return o.HTTPServer(((*HTTPServerArgs)(args)))
		}
	}
	return &plugin.Options{
		Writer:     o.Writer,
		Flagset:    o.Flagset,
		Fetch:      o.Fetch,
		Sym:        sym,
		Obj:        obj,
		UI:         o.UI,
		HTTPServer: httpServer,
	}
}

// HTTPServerArgs contains arguments needed by an HTTP server that
// is exporting a pprof web interface.
type HTTPServerArgs plugin.HTTPServerArgs

// Options groups all the optional plugins into pprof.
type Options struct {
	Writer     Writer
	Flagset    FlagSet
	Fetch      Fetcher
	Sym        Symbolizer
	Obj        ObjTool
	UI         UI
	HTTPServer func(*HTTPServerArgs) error
}

// Writer provides a mechanism to write data under a certain name,
// typically a filename.
type Writer interface {
	Open(name string) (io.WriteCloser, error)
}

// A FlagSet creates and parses command-line flags.
// It is similar to the standard flag.FlagSet.
type FlagSet interface {
	// Bool, Int, Float64, and String define new flags,
	// like the functions of the same name in package flag.
	Bool(name string, def bool, usage string) *bool
	Int(name string, def int, usage string) *int
	Float64(name string, def float64, usage string) *float64
	String(name string, def string, usage string) *string

	// BoolVar, IntVar, Float64Var, and StringVar define new flags referencing
	// a given pointer, like the functions of the same name in package flag.
	BoolVar(pointer *bool, name string, def bool, usage string)
	IntVar(pointer *int, name string, def int, usage string)
	Float64Var(pointer *float64, name string, def float64, usage string)
	StringVar(pointer *string, name string, def string, usage string)

	// StringList is similar to String but allows multiple values for a
	// single flag
	StringList(name string, def string, usage string) *[]*string

	// ExtraUsage returns any additional text that should be
	// printed after the standard usage message.
	// The typical use of ExtraUsage is to show any custom flags
	// defined by the specific pprof plugins being used.
	ExtraUsage() string

	// Parse initializes the flags with their values for this run
	// and returns the non-flag command line arguments.
	// If an unknown flag is encountered or there are no arguments,
	// Parse should call usage and return nil.
	Parse(usage func()) []string
}

// A Fetcher reads and returns the profile named by src, using
// the specified duration and timeout. It returns the fetched
// profile and a string indicating a URL from where the profile
// was fetched, which may be different than src.
type Fetcher interface {
	Fetch(src string, duration, timeout time.Duration) (*profile.Profile, string, error)
}

// A Symbolizer introduces symbol information into a profile.
type Symbolizer interface {
	Symbolize(mode string, srcs MappingSources, prof *profile.Profile) error
}

// MappingSources map each profile.Mapping to the source of the profile.
// The key is either Mapping.File or Mapping.BuildId.
type MappingSources map[string][]struct {
	Source string // URL of the source the mapping was collected from
	Start  uint64 // delta applied to addresses from this source (to represent Merge adjustments)
}

// An ObjTool inspects shared libraries and executable files.
type ObjTool interface {
	// Open opens the named object file. If the object is a shared
	// library, start/limit/offset are the addresses where it is mapped
	// into memory in the address space being inspected.
	Open(file string, start, limit, offset uint64) (ObjFile, error)

	// Disasm disassembles the named object file, starting at
	// the start address and stopping at (before) the end address.
	Disasm(file string, start, end uint64) ([]Inst, error)
}

// An Inst is a single instruction in an assembly listing.
type Inst struct {
	Addr     uint64 // virtual address of instruction
	Text     string // instruction text
	Function string // function name
	File     string // source file
	Line     int    // source line
}

// An ObjFile is a single object file: a shared library or executable.
type ObjFile interface {
	// Name returns the underlying file name, if available.
	Name() string

	// Base returns the base address to use when looking up symbols in the file.
	Base() uint64

	// BuildID returns the GNU build ID of the file, or an empty string.
	BuildID() string

	// SourceLine reports the source line information for a given
	// address in the file. Due to inlining, the source line information
	// is in general a list of positions representing a call stack,
	// with the leaf function first.
	SourceLine(addr uint64) ([]Frame, error)

	// Symbols returns a list of symbols in the object file.
	// If r is not nil, Symbols restricts the list to symbols
	// with names matching the regular expression.
	// If addr is not zero, Symbols restricts the list to symbols
	// containing that address.
	Symbols(r *regexp.Regexp, addr uint64) ([]*Sym, error)

	// Close closes the file, releasing associated resources.
	Close() error
}

// A Frame describes a single line in a source file.
type Frame struct {
	Func string // name of function
	File string // source file name
	Line int    // line in file
}

// A Sym describes a single symbol in an object file.
type Sym struct {
	Name  []string // names of symbol (many if symbol was dedup'ed)
	File  string   // object file containing symbol
	Start uint64   // start virtual address
	End   uint64   // virtual address of last byte in sym (Start+size-1)
}

// A UI manages user interactions.
type UI interface {
	// Read returns a line of text (a command) read from the user.
	// prompt is printed before reading the command.
	ReadLine(prompt string) (string, error)

	// Print shows a message to the user.
	// It formats the text as fmt.Print would and adds a final \n if not already present.
	// For line-based UI, Print writes to standard error.
	// (Standard output is reserved for report data.)
	Print(...interface{})

	// PrintErr shows an error message to the user.
	// It formats the text as fmt.Print would and adds a final \n if not already present.
	// For line-based UI, PrintErr writes to standard error.
	PrintErr(...interface{})

	// IsTerminal returns whether the UI is known to be tied to an
	// interactive terminal (as opposed to being redirected to a file).
	IsTerminal() bool

	// WantBrowser indicates whether browser should be opened with the -http option.
	WantBrowser() bool

	// SetAutoComplete instructs the UI to call complete(cmd) to obtain
	// the auto-completion of cmd, if the UI supports auto-completion at all.
	SetAutoComplete(complete func(string) string)
}

// internalObjTool is a wrapper to map from the pprof external
// interface to the internal interface.
type internalObjTool struct {
	ObjTool
}

func (o *internalObjTool) Open(file string, start, limit, offset uint64) (plugin.ObjFile, error) {
	f, err := o.ObjTool.Open(file, start, limit, offset)
	if err != nil {
		return nil, err
	}
	return &internalObjFile{f}, err
}

type internalObjFile struct {
	ObjFile
}

func (f *internalObjFile) SourceLine(frame uint64) ([]plugin.Frame, error) {
	frames, err := f.ObjFile.SourceLine(frame)
	if err != nil {
		return nil, err
	}
	var pluginFrames []plugin.Frame
	for _, f := range frames {
		pluginFrames = append(pluginFrames, plugin.Frame(f))
	}
	return pluginFrames, nil
}

func (f *internalObjFile) Symbols(r *regexp.Regexp, addr uint64) ([]*plugin.Sym, error) {
	syms, err := f.ObjFile.Symbols(r, addr)
	if err != nil {
		return nil, err
	}
	var pluginSyms []*plugin.Sym
	for _, s := range syms {
		ps := plugin.Sym(*s)
		pluginSyms = append(pluginSyms, &ps)
	}
	return pluginSyms, nil
}

func (o *internalObjTool) Disasm(file string, start, end uint64) ([]plugin.Inst, error) {
	insts, err := o.ObjTool.Disasm(file, start, end)
	if err != nil {
		return nil, err
	}
	var pluginInst []plugin.Inst
	for _, inst := range insts {
		pluginInst = append(pluginInst, plugin.Inst(inst))
	}
	return pluginInst, nil
}

// internalSymbolizer is a wrapper to map from the pprof external
// interface to the internal interface.
type internalSymbolizer struct {
	Symbolizer
}

func (s *internalSymbolizer) Symbolize(mode string, srcs plugin.MappingSources, prof *profile.Profile) error {
	isrcs := MappingSources{}
	for m, s := range srcs {
		isrcs[m] = s
	}
	return s.Symbolizer.Symbolize(mode, isrcs, prof)
}