package procstat

import (
	"time"
	"regexp"
	"strconv"

	"github.com/shirou/gopsutil/process"

	"github.com/influxdata/telegraf"
)

type SpecProcessor struct {
	Prefix string
	tags   map[string]string
	fields map[string]interface{}
	acc    telegraf.Accumulator
	proc   *process.Process
}

func NewSpecProcessor(
	processName string,
	prefix string,
	cmdlineRegex string,
	parentCmdlineRegex string,
	acc telegraf.Accumulator,
	p *process.Process,
	tags map[string]string,
) *SpecProcessor {
	if processName != "" {
		tags["process_name"] = processName
	} else {
		name, err := p.Name()
		if err == nil {
			tags["process_name"] = name
		}
	}

	if cmdlineRegex != "" {
		val := CmdlineSubstrings(p, &cmdlineRegex)
		for i, value := range val {
			tags["cmdline." + strconv.Itoa(i)] = value
		}
	}

	ppid, err := p.Ppid()
	if err == nil {
		tags["ppid"] = strconv.Itoa(int(ppid))

		pp, err := process.NewProcess(ppid)
		if err == nil {
			parentName, err := pp.Name()
			if err == nil {
				tags["parent_name"] = parentName
			}
			if parentCmdlineRegex != "" {
				val := CmdlineSubstrings(pp, &parentCmdlineRegex)
				for i, value := range val {
					tags["pcmdline." + strconv.Itoa(i)] = value
				}
			}
		}
	}

	return &SpecProcessor{
		Prefix: prefix,
		tags:   tags,
		fields: make(map[string]interface{}),
		acc:    acc,
		proc:   p,
	}
}

func CmdlineSubstrings(p *process.Process, regex *string) []string {
	cmdline, err := p.Cmdline()
	if err == nil {
		re, err := regexp.Compile(*regex)
		if err == nil {
			cmdlineSubmatch := re.FindStringSubmatch(cmdline)
			if cmdlineSubmatch != nil {
				return cmdlineSubmatch[1:]
			}
		}
	}
	return nil
}

func (p *SpecProcessor) pushMetrics() {
	var prefix string
	if p.Prefix != "" {
		prefix = p.Prefix + "_"
	}
	fields := map[string]interface{}{}

	numThreads, err := p.proc.NumThreads()
	if err == nil {
		fields[prefix+"num_threads"] = numThreads
	}

	fds, err := p.proc.NumFDs()
	if err == nil {
		fields[prefix+"num_fds"] = fds
	}

	ctx, err := p.proc.NumCtxSwitches()
	if err == nil {
		fields[prefix+"voluntary_context_switches"] = ctx.Voluntary
		fields[prefix+"involuntary_context_switches"] = ctx.Involuntary
	}

	io, err := p.proc.IOCounters()
	if err == nil {
		fields[prefix+"read_count"] = io.ReadCount
		fields[prefix+"write_count"] = io.WriteCount
		fields[prefix+"read_bytes"] = io.ReadBytes
		fields[prefix+"write_bytes"] = io.WriteCount
	}

	cpu_time, err := p.proc.Times()
	if err == nil {
		fields[prefix+"cpu_time_user"] = cpu_time.User
		fields[prefix+"cpu_time_system"] = cpu_time.System
		fields[prefix+"cpu_time_idle"] = cpu_time.Idle
		fields[prefix+"cpu_time_nice"] = cpu_time.Nice
		fields[prefix+"cpu_time_iowait"] = cpu_time.Iowait
		fields[prefix+"cpu_time_irq"] = cpu_time.Irq
		fields[prefix+"cpu_time_soft_irq"] = cpu_time.Softirq
		fields[prefix+"cpu_time_steal"] = cpu_time.Steal
		fields[prefix+"cpu_time_stolen"] = cpu_time.Stolen
		fields[prefix+"cpu_time_guest"] = cpu_time.Guest
		fields[prefix+"cpu_time_guest_nice"] = cpu_time.GuestNice
	}

	cpu_perc, err := p.proc.Percent(time.Duration(0))
	if err == nil && cpu_perc != 0 {
		fields[prefix+"cpu_usage"] = cpu_perc
	}

	mem, err := p.proc.MemoryInfo()
	if err == nil {
		fields[prefix+"memory_rss"] = mem.RSS
		fields[prefix+"memory_vms"] = mem.VMS
		fields[prefix+"memory_swap"] = mem.Swap
	}

	p.acc.AddFields("procstat", fields, p.tags)
}