package hledger

import (
	"bytes"
	"encoding/json"
	"errors"
	"os/exec"

	"github.com/tgrosinger/ledger-tui/pkg/transaction"
	tx "github.com/tgrosinger/ledger-tui/pkg/transaction"
)

// HLedger implements the Ledger interface. It uses the hledger binary to pull
// data from the ledger file.
type HLedger struct {
	filepath string
}

func New(filepath string) HLedger {
	return HLedger{
		filepath: filepath,
	}
}

// GetTransactions returns a slice of transactions loaded from the configured
// ledger file.
func (hl HLedger) GetTransactions() ([]tx.Transaction, error) {
	out, err := hl.exec("print", "-O", "json")
	if err != nil {
		return nil, err
	}

	var results []Transaction
	err = json.Unmarshal([]byte(out), &results)
	if err != nil {
		return nil, err
	}

	converted, errors := hl.convertTransactions(results)
	return converted, transaction.TransactionParseErrors{
		Errors: errors,
	}
}

func (hl HLedger) AddTransaction(newTx tx.Transaction) error {
	return errors.New("Method not implemented")

}

// exec runs an hledger command against the configured ledger file.
func (hl HLedger) exec(args ...string) (string, error) {
	allArgs := make([]string, 0, len(args)+2)
	allArgs = append(allArgs, "-f", hl.filepath)
	allArgs = append(allArgs, args...)

	cmd := exec.Command("hledger", allArgs...)

	var out bytes.Buffer
	cmd.Stdout = &out

	err := cmd.Run()
	if err != nil {
		return "", err
	}

	return out.String(), nil
}

// convertTransaction converts the transactions as loaded from hledger into a
// friendlier and simplified format used by this application.
func (hl HLedger) convertTransactions(txs []Transaction) ([]transaction.Transaction, []transaction.TransactionParseError) {
	output := make([]transaction.Transaction, 0, len(txs))
	errors := make([]transaction.TransactionParseError, 0)
	for _, tx := range txs {
		converted, err := tx.convert()
		if err != nil {
			position := -1
			if len(tx.Tsourcepos) > 0 {
				position = tx.Tsourcepos[0].SourceLine
			}
			errors = append(errors, transaction.TransactionParseError{
				Err:         err,
				Date:        tx.Tdate,
				Description: tx.Tdescription,
				Line:        position,
			})
		} else {
			output = append(output, converted)
		}
	}
	return output, errors
}

// Transaction is the data format for transactions as they come from hledger
// when executing `hledger print -O json`.
type Transaction struct {
	Tcode        string `json:"tcode"`
	Tcomment     string `json:"tcomment"`
	Tdate        string `json:"tdate"`
	Tdate2       string `json:"tdate2"`
	Tdescription string `json:"tdescription"`
	Tindex       int    `json:"tindex"`
	Tpostings    []struct {
		Paccount string `json:"paccount"`
		Pamount  []struct {
			Acommodity string      `json:"acommodity"`
			Aprice     interface{} `json:"aprice"`
			Aquantity  struct {
				DecimalMantissa int     `json:"decimalMantissa"`
				DecimalPlaces   int     `json:"decimalPlaces"`
				FloatingPoint   float64 `json:"floatingPoint"`
			} `json:"aquantity"`
			Astyle struct {
				Ascommodityside   string      `json:"ascommodityside"`
				Ascommodityspaced bool        `json:"ascommodityspaced"`
				Asdecimalpoint    string      `json:"asdecimalpoint"`
				Asdigitgroups     interface{} `json:"asdigitgroups"`
				Asprecision       int         `json:"asprecision"`
			} `json:"astyle"`
		} `json:"pamount"`
		Pbalanceassertion interface{} `json:"pbalanceassertion"`
		Pcomment          string      `json:"pcomment"`
		Pdate             interface{} `json:"pdate"`
		Pdate2            interface{} `json:"pdate2"`
		Poriginal         interface{} `json:"poriginal"`
		Pstatus           string      `json:"pstatus"`
		Ptags             []string    `json:"ptags"`
		Ptransaction      string      `json:"ptransaction_"`
		Ptype             string      `json:"ptype"`
	} `json:"tpostings"`
	Tprecedingcomment string `json:"tprecedingcomment"`
	Tsourcepos        []struct {
		SourceColumn int    `json:"sourceColumn"`
		SourceLine   int    `json:"sourceLine"`
		SourceName   string `json:"sourceName"`
	} `json:"tsourcepos"`
	Tstatus string   `json:"tstatus"`
	Ttags   []string `json:"ttags"`
}

func (t *Transaction) convert() (transaction.Transaction, error) {
	tx := transaction.Transaction{
		Index:             t.Tindex,
		Date:              t.Tdate,
		Description:       t.Tdescription,
		Comment:           t.Tcomment,
		PreceedingComment: t.Tprecedingcomment,
		Postings:          make([]transaction.Posting, len(t.Tpostings)),
		Status:            t.Tstatus,
		Tags:              t.Ttags,
	}

	for _, posting := range t.Tpostings {
		tx.Postings = append(tx.Postings, posting.convert())
	}

	return tx, nil
}